I'll start with the finished product, which I trust I'll have and love for many years. The chairs are awesome, unique, and subtly stylish. I love them. They're very cool. 5 stars.
But...OMG putting them together was such a pain in the ass. The crossmember supports (5a and 5b) below the seat each take 4 hex key screws and the bore and cavity is not cut by a jig that would grant easy access to the screw with the tool. Instead you're struggling trying to thread the screw, and then making 1/8th turns each time you re-seat the wrench. It's a very frustrating process. Here's what I learned after putting 4 chairs together:
1. Employ the help of another human. No joke. Two people is a must, BUT only partner with one which you have a healthy relationship!
2. Have cool mellow music playing, like Bob Marley.
3. Assemble the chair in its stand-up normal position. If you lay it on its side or back you'll definitely get a wobbly chair.
3. Don't fully tighten anything at once, even the backrest screws. Rotate through the 4-6 screws, like you would a tire lug nut pattern and intermittently snug the 4-6 screws for 5a and 5b and the back rest so that the sides of the chair come together at an even pace. Too much tension on one element puts the others out of whack and you might be left with a wobbler.
4. invent or employ a power tool to take assembly frustration level from 9.5/10 to 1.5/10.