I didn't want the mull or the tapes show through at all, but also had the edges of the leather to level out so I decided to wedge mull and tapes between cover and the cardboard to even out the leather edges. At this size it was a bit tricky to work but eventually worked out well. My only woe is, I should have broken the edge of t he cardboard towards the spine a bit better to soften the step between board and hinge area.

I also added a piece of cardboard to level the turn ins on the spine stiffener. I can go well with thin materials, but as soon as the covering material is a bit thicker it curves the spine a little and I don't like that. So leveling it out it is for me.

When I glue down the tapes and the mull I held the case open in about a 45° angle to allow it to sit tight in the case, but also give it some range of motion without getting bulky when closed or pulling the text out too far when opening it. For that I pushed down the cover, held the board at an angle and worked up the tapes and mull before closing it and letting it dry with a moisture barrier between the cover and the endpaper.

Next step was gluing in the cardboard to level out the turn ins. Pressing them in and then pasting down the paste down.

I had just rounded the spine and glued the tube on the book spine against the spine of the cover, when I noticed the front edge has gotten a bit short delicate (sometimes that happens), but it made me worry that with the stretching of the paper I’d end up with just a tiny strip of front edge. So I cut back the paste down about a mm to prevent that.

When applying glue (or any moisture for that matter), paper stretches which can be a hassle if unaccounted for. With Chiyogami the stretch is not as bad as I feared, but it still made up half of what I cut back. Being shorter than necessary is ok in this case though. When the book is closed no one will notice the paste down is actually a bit smaller than the innerbook and when it’s open, well, then it makes for a good looking front edge. The only must here is, USE SOME MACULATION WHEN APLLYING GLUE.  I forgot that once and it would have been fine had both my endpapers had the same size...  as it was I had a very neat strip of glue on the fly leaf...

I closed push down the hinge and close the cover only lightly just to lift it up a tiny bit again and check if the endpaper is straight or askew. Because the endpaper is only lightly attached to the cover it can be carefully corrected if necessary before I turn to the other endpaper.  When both are done I apply some short, but heavy pressure to get the paste down to stick firmly to the cover. Take it out of the press and check immediately for emerging glue on the paste down. This is a bit tricky, because the cover needs to be opened far enough to wipe away any excess glue, but the glue is still fresh enough that the paper can be pulled out of place if opened carelessly or too far, which would result in nasty wrinkles close to the inner hinge.  I prevent that by pushing down the cover so the inner hinge gets kind of clamped  and can’t move too much while opening the book a bit.  It looks somewhat like this:

When the book is clean I put thin cardboards between paste down and fly leaf and align them with the cover board without blocking the hinge. The cardboard is to prevent the glue-moisture from wandering into the inner book and make everything wavy. Instead it can wander into the cardboard without doing any harm. Then I settle the book between more clean cardboard (I use finnboard, but any cardboard will do, it only has to absorb the moisture and protect the cover from scratches), weigh it down and let it dry.