I was having trouble adjusting the feel of the J3 bearings. Upon closer inspection, It looks like the flathead screws are slightly proud of the surface. I hated to do it to the nice anodized part, but I used a diamond stone to lap the screws flush with the surface. The bearings feel much better now.

Parts are bead blasted and anodized matte black. Assembly Is under way.

I am also working my way through the AR3 electrical cabinet build. The instructions do not mention wiring the 5v aviation plug. There is also no mention how the teensy and Mega board are powered. Nt sure if I should wire to the internal 5v supply or let the USB power these boards. Either will likely work, but it would be good to know what was intended.

I may send the aluminum pieces out for bead blast and black anodizing, not sure yet. My 5v power supply did not have mounting holes like Chris's, so I 3d printed a bracket which mount to the two holes in the bottom of the supply. I also had a difficult time marking the larger power supply mounting holes using the paper method, so I 3d printed a drill guide which worked great. I don't have a picture of it, but here is a render. The bottom ledge rests on the grid board, and the cutout on the lower right side is so that it can reference the side wall of the cabinet without hitting the inside radius.