Thanks to LivInLaVidaNeko on reddit:

Here's a revised diagram which also includes the little shards to indicate the primary type of each crafter!

Important to note that while each crafter has two elements, only one is always the primary element that'll be used for ingredients. Only during crafts for gear, furniture, etc. uses the secondary element, and sometimes for less than the primary element. Crafter: Primary/Secondary CRP: Wind/Ice BSM: Fire/Earth ARM: Ice/Earth GSM: Wind/Fire LTW: Earth/wind WVR: Lightning/Wind ALC: Water/lightning CUL: Fire/Water So for omnicrafters (assuming you'd craft a balanced amount on each craft) you'd need more shards and crystals of fire (which is primary for 2 and secondary to 1) than Earth (which is only primary for LTW and secondary for 2), Pivoting the data from above to the elements gives us the below list. Bold ones are use the element as it's primary Fire: BSM CUL GSM Ice: ARM CRP Wind: CRP GSM LTW WVR Earth: LTW BSM ARM Lightning: WVR ALC Water: ALC CUL