1.9 Bead Lock 6 Spoke

thingiverse

It's a simple design, fits on 12mm hex hubs and has a nice off set on the rims. Lock the beads in place with 6 3mm bolts. Getting the tyres to go in is a wee bit tricky, but they hold nice and snug. :-) Print them on 100% infill to make them as strong as possible. The pieces go flat on the ground facing up, print the beads without support, but for the rim and the ring, you want touching buildplate support on 80 degree overhang.