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I made another version of my PCB that uses BNO-Style PCBs (etc BNO085, 86 and 80. I used the official SlimeVR BNO layout for this, and wired up all of the connections myself. As this is compatible with both official SlimeVR BNO085 breakout boards and ones from Aliexpress.

Here is the extension, which sadly has to be 2 sided due to space constraints, which increases cost. It runs through a connector which I copied off of the official SlimeVR board.

After ordering and examining my design, I decided to swap around the extension connector and the IMU slot, as it increases the clearance for the battery JST connector.

This design ends up simplifying the traces too, so it's better overall. I also made a simple Extension board, inspired by the official SlimeVR extension board for BNO-Style slimes. It's a very simple design, designed with holes to fit in a case that I'd make if I had the time.

George helped me work in Fusion 360 a little to make a rounded screw insert in the bottom for use with trackstraps, which are leagues more comfortable from my experience than the cheap amazon straps I'm using currently. It was fairly easy to add the insert, as all I needed to do was make the bottom a face in Fusion, thicken it and then add how deep i wanted the insert. This took a while though and ended up frustrating both me and George.

Here is what the new case looks like on the bottom.

I also removed the wings, as I found them cumbersome when trying them with the new straps.

After taking some part schematics from other projects like I explained in the previous post, I got to making my own version of the PCB. The very first thing I did was make a new schematic, replacing the old AUX-IMU holes with a much cleaner 5 pin JST-ZH 1.5mm connector, which is the same connector the official SlimeVR trackers use to power, ground and receive information. This means that the cables are no longer hard soldered, increasing both reliability and repairability, as the cables can be immediately replaces and there is little to no chance of the soldering joint from coming off.

Here is a photo of my new schematic, I removed an optional jumper for skipping including diodes, as I believe charging protection is important and it was taking up valuable space ontop of the PCB.

When making the PCB, I wanted it to all be topside to use JLCPCB's economic part placement to save money, so I had to make all of the traces on the top side.

I first used EasyEDA's auto-routing to place down the traces, which finds the most efficient way to place all of the traces, but at cost to not placing them all.

Tt ended out like this for my first design, with the red lines being traces, grey being pads and blue lines are traces that need to be connected but are not.

I used inspiration from Alex for one of the connections and ran the other around the board for the resistor, which although not ideal, does not affect the signal of the connection, so it ends up fine. I ended up ordering that first design, and It has been a pleasure to build with since I got it, although I believe i may have made a mistake making this trace too close to the holes as there are charging issues on the current design, this is something that I can easily fix by moving the traces only slightly down.

I took my prototype 2 SlimeVRs over to my friend George's house for him to test, he had alot of feedback and I helped him through the setup process. The first thing that happened was the trackers not even connecting to George's PC, this is not shown clearly in SlimeVR server that this was the issue, nor was there an obvious FAQ for connection issues.

I troubleshooted by checking to see if I could hear the windows connect noise when I plugged a tracker in via USB, and I couldn't. Then I checked the connected devices in the system properties and saw there were driver issues, so I had to dig deep into SlimeVR's documentation to find the link to the drivers, as they never installed properly with SlimeVR server, even though they should have. After connecting all of the trackers to SlimeVR server, I helped George put on the trackers and taught him how to do the weird proportions dance and mounting reset.

George wearing the trackers, all circled in red with some hidden but just above his knees.

Once done he loaded up VRChat to test out the tracking, which is when we recorded this video: This video showcases me guiding George through alot of the processes that come with using SlimeVR, as well as the large learning curve that comes with using it.

After finishing up, George mentioned how the trackers dug in to his body, and to mitigate this in future versions, I'll round the corners of the case and suggest gluing some thin foam to the bottom of them to increase comfort.

I know utterly nothing about PCB design, so the first thing I did was look to see what software Alec Probst used, who is the person who made the PCB that was in prototype 2.

Alec used KiCAD, which is an open-source EDA (Electronic Design Automation software). It's main benefit is the customisability of being an open-source project. It ends up being a drawback too though, as KiCAD feels dated compared to some other EDA programs, and the UI is an utter mess. I struggled with KiCAD for a while, pretty much just staring at it until I could understand what is going on. The documentation wasn't much use at all, although I did read getting started in KiCad and a little into the schematic editor documentation.

Images of the KiCAD UI

Soon after just staring at Alec's design in KiCad and realising I am way out of my depth with the program, I started looking at an alternative, EasyEDA. Easy EDA is the software that the official SlimeVR team use, therefore I had a chance to look at their PCB designs and schematics as well as take some parts that I needed, as they are open-source. I found EasyEDA much easier to work with, as it comes with a long list of online schematics for parts that you don't need to manually import, and I had the chance to take a few designs from other people's open source SlimeVR projects, like the BNO-style connector on the official SlimeVR PCB, and Gorbit99's BMI-style connector for use on my project.

I spent alot of time staring at the schematic of Alec's PCB Before I decided to any edits to it, even importing it into EasyEDA as it has an option to import KiCAD projects.

Alec's PCB in EasyEDA

PCB design is separated into two parts, the schematic phase and the PCB building phase, both need eachother to work, as you can not design a PCB without them.

The schematic phase is laying out what components you need and how they connect onto a 2D surface. This is for the EDA to know what traces need to go to where. Here is an example of the official SlimeVR extension PCB schematic for example. It may look complicated, but all it's showing is that the named pins from the module connect to the connector (named CN2), with some going through C1 first before making their way to the module.

this is a picture of that same design in PCB form, which shows off how simple it really is. Red lines are on the top of the PCB, and blue lines are on the bottom, making this a 2 sided PCB.

Most EDA software has the ability to view the PCB in 3D, which shows what it would look like in person. Here is an example of that same PCB in 3D Looks like.

My process for rapid case prototyping is to print a single case, and test fit it with a PCB without all parts on it, but without an IMU. This is to test the fit with a realistic prototype rather than just doing guesswork. I usually set a prototype to print before I go for a period of time, such as before college, work or going to sleep, so by the time I get back I can immediately start working on the prototype. This has been very very effective, as I can tell immediately when things are and are not working.

An example of my prototyping board sitting in a case

With rapid prototyping now sorted out, I've started learning blender myself to try and make edits to the case easily. It's been slow progress so far, with my friend George coaching me on different things to expand my currently limited blender experience. I've decided to keep the top of the case the same, as it needs no editing and the design is both functional and looks good visually.

This means I needed to edit the bottom of the case, and by using the extrude tool, along with learning how to dissolve faces and add cubes, I evolved the case over 5 designs, with iterative testing with a half made slimevr to test fit everything.

Here is a picture of all of my prototypes I did myself, i'll explain how I went iterating them over time.

Version 1 The first thing i noticed was how in prototype 2, my batteries were being pierced by the sharp edges formed after trimming down the solder joints, and how the battery had no proper place to sit, so that's the first thing I tried to Improve. By adding a small barrier around the inside of the case to let the battery drop down into it. I printed this version and the bottom of the case pierced from being too thin.

Version 2

All I did in this version was make the bottom of the case thicker, which fixed the issue of it piercing. Although the large sharp corners dug into my skin when tested with a strap over the case.

Version 3

I changed the bottom of the case to use a smaller platform to thicken the bottom of the case, I also added a small cutout to the side of the barrier, to allow for the cables of the battery to go out to the top, as I planned to switch to 2 pin JST connectors for the battery, and they could not fit in the bottom of the case due to there not being enough space.

Version 4 I made the cutout bigger and lower down, as in my testing there was not ample enough space for the cable of the battery to fit through. I also removed 2 out of the 3 standoffs, as they kept snapping off in my testing and fitting the PCBs inside of the cases. I still needed one to keep the PCB stable and in-place.

Version 5 I added small standoffs to every corner, to make sure the PCB would not pierce the battery anymore while maintaining space to easily fit into the hole. This design has worked well since I made it, and I plan to make all of the trackers with this design as I believe it will be durable and long-lasting.

After getting a functional design for prototype 2 through my conversations with George, I made a full set of Slimes. The building process was fairly easy and short with Alec's guide. In total it took me about 3.5-4 hours to make a full set of 5, which for my first time building them was pretty good, and much shorter than the 1.5 hours each it used to take me with prototype 1.

Pictures of the trackers almost done, only missing IMUs as they hadn't arrived yet.

A picture of me testing the hip to chest extension tracker. This came at a later date due to me not having enough working IMUs, and is something i plan to improve as I do not like having hard-soldered cables

A picture of the ports of a working tracker, with a strap put onto it.

I used the website JLCPCB to order my PCBs, as they are highly recommended by the SlimeVR community, no matter what PCB you order. The process is fairly simple if you already have the "gerber" files, which are the files with all of the data for the PCB, and where the components on it go. Two other files, known as a "bill of materials" and the "pick and place" file are for the manufacturers to know what order the parts should be, and what the parts are. As I already had the gerber files for the PCB from Alec Probst, it was as simple as dropping the file in, and pressing on the settings he reccomended.

After doing this, all I had to do was press continue a few times then go to the checkout process. All in the process only cost $7.80 for 10 PCBs, after taxes and shipping. The package arrived at my house in 8 days.

The new case design was leagues improved over the awful boxes I used. With a cleaner layout now possible due to the PCB, wings added to the case to keep the trackers in place under the straps and an overall size footprint decrease both in the Y and Z axis.

Philippe Starck:

Who is Philippe Starck? Philippe Starck is a French designer known for making unusual household products. He’s been designing things like chairs, lemon squeezers, and toothbrushes since the 1980s. His stuff doesn’t always focus on being the most useful, but instead appearing more like art pieces than functional furniture or household items.

Starck became well known after working with companies like Alessi and Kartell. He got attention for making products that looked different from anything else, like the Juicy Salif lemon squeezer. It looks like some kind of alien tripod.

How does Starck design stuff? Starck doesn’t follow the usual rules when it comes to designing products. Instead of just focusing on what works best, he tries to make things that feel special. Sometimes that means it’s harder to use, but it’s more fun or interesting.

A good example is the Louis Ghost Chair. It’s made from clear plastic, but it looks like a fancy old chair from a palace. It's design is intended to be practical as well as look well, with it being waterproof and easily stackable.

He usually uses materials like plastic and metal because they can be shaped easily and are good for mass production. Starck works with manufacturers who figure out how to build the products properly while he focuses on the idea and shape.

Sir Jony Ive:

Who is Sir Jony Ive? Sir Jony Ive is a British designer who led the design team at Apple for over 20 years. He’s the person behind the look and feel of some of Apple’s most famous products, like the iMac, iPod, iPhone, and MacBook. His work focuses on making things as simple and clean as possible, removing anything that isn’t necessary.

Jony started working at Apple in the early 90s, but really became well known after Steve Jobs returned to the company in 1997. Together, they changed the direction of Apple by making design the most important part of the product. Jony’s designs helped turn Apple from a struggling tech company into one of the biggest brands in the world.

How does Jony Ive design stuff? Jony’s design style is all about simplicity. He tries to make products that are easy to use and don’t have any extra parts that aren’t needed. His goal is for the product to explain itself, so you know how to use it just by looking at it.

One of the best examples is the iPhone. There are no buttons except for the ones you absolutely need, and the shape is smooth and minimal. Another good example is the iMac G3, which was one of the first computers to come in different colors. It had a handle on top so you could carry it, and all the parts were in one shell to keep it clean and simple.

He also helped design the MacBook, iPod, and Apple Watch, which all follow the same idea—simple shapes, smooth edges, and as few buttons as possible. Most Apple products from the 2000s and 2010s have that same look because of him.

Materials / Manufacturing: Jony’s team worked closely with Apple’s engineers and manufacturers to figure out how to build products the way they imagined. They used materials like aluminum and glass, which not only looked good but made the devices feel strong and high quality. A lot of time was spent figuring out tiny details, like how a button should feel or how the edges should be rounded.

What are the Red Dot Awards? The Red Dot Awards are one of the biggest international design competitions in the world. They cover all kinds of design—products, brands, and even user interfaces. If something wins a Red Dot, it usually means it has really good design, not just in how it looks, but how it works too.

The awards started in Germany in 1955, and over time they’ve grown to include entries from all over the world. Every year, thousands of designers and companies submit their work hoping to get the Red Dot label, which is seen as a mark of high-quality design. Winning a Red Dot can help boost a product's popularity or a designer’s career.

Red Dot Awards:

What are the Red Dot Awards?

The Red Dot Awards are one of the biggest international design competitions in the world. They cover all kinds of design—products, brands, and even user interfaces. If something wins a Red Dot, it usually means it has really good design, not just in how it looks, but how it works too.

The awards started in Germany in 1955. Every year, thousands of designers and companies submit their work hoping to get the Red Dot label, which is seen as a mark of high-quality design. Winning a Red Dot can help boost a product's popularity or a designer’s career.

How do the Red Dot Awards work? Categories: The awards are split into three main sections, Product Design, Brand & Communication Design, and Design Concept. Product Design is the biggest one and includes everything from furniture and electronics to vehicles and household tools. Brand & Communication focuses more on things like packaging, logos, and websites. Design Concept is for ideas and prototypes that haven’t been released yet.

Judging: A panel of expert judges from around the world looks at each entry. They don’t just judge by looks, they also check how well something works, how it’s made, how easy it is to use, and how innovative it is. The process is done in person, and each product is tested or looked at directly when possible.

Winners get to use the Red Dot logo on their product or packaging, and they’re featured in the Red Dot yearbook, the official website, and sometimes displayed in the Red Dot Museum in Germany.

Japanese Stationary Awards:

What are the Japanese Stationery Awards? The Japanese Stationery Awards are annual competitions that highlight some of the best-designed stationery products in Japan. These awards focus on both how the product looks and how useful it is in real life. Most of the winners are things that improve everyday tasks, like writing, cutting, or organizing, with small but clever design changes.

The awards have gained a lot of attention, especially in Japan where stationery is a big part of daily life and culture. Many of the products that win end up becoming really popular, and some even get picked up by international stores.

How do the Japanese Stationery Awards work? There are different award events across the year. The biggest one is the ISOT Stationery of the Year, which happens at Japan’s main stationery trade show in Tokyo. There are also user-focused awards like Bungu Joshi Haku (Stationery Girls Expo), where fans vote for their favorites.

Products are judged in categories like:

Functionality - how useful the item is in everyday life

Design - how clean, smart, or fun it looks and feels

Innovation - whether it solves a problem in a new way

Popularity - what real users are actually excited to use

Getting into home 3D printing on a budget has been both exciting and overwhelming. So far, I’ve focused on FDM printers, as I believe that they'll produce a more durable product than resin printers, along with having less word needed to produce a good print.

For the actual hardware, I’ve been looking into budget-friendly printers that are highly recommended by the community. The Creality Ender 3 series keeps coming up, along with the Elegoo Neptune, Anycubic Kobra and the Bambu Lab A1 Mini. They’re all in the £150–£300 range and seem to have solid reputations. I’m also keeping an eye out for refurbished units or second-hand deals locally, which could make things even more affordable. Resin printers like the Elegoo Mars seem good too, especially for finer detail, but I’m holding off since resin handling adds complexity and cost that I do not feel like the average home user, such as myself needs.

After buying my printer, which ended up being a 2nd hand Ender 3 Pro, I got it started within a few hours of getting home. Using the recommended slicer Ultimaker Cura, which is an open-source slicer that's largely used by the community.

Materials are surprisingly varied, but for now I’m sticking with PLA since it’s cheap, easy to print, and works well for most home projects. I did learn that filament needs to be stored properly because humidity can ruin it, so I’ve started keeping mine in a sealed container with silica gel packs. There’s a ton of free knowledge out there if you dig a little. Reddit has been helpful, especially r/3Dprinting and r/ender3 for beginner tips.

The first step of the design of Alec's case was adding wings to hold in straps, as without them the trackers would just fall out with any sudden movement. I talked to my friend George who knows how to use Blender to help me while I learnt how to.