I designed this adapter to mount a GPS or phone holder that use the AMPS holes pattern on a 28,6mm handlebar, and 4 screw and 3×5mm rilsan bracelets.
This diameter is the same on some naked bike such as MT-09 and is very common on off-road bikes.
This model is supposed to be printed with 2 materials :
This is a larger version of the previous one posted previously.
The author remixed this model.
Larger version designed for a Sherco Handlebar so for the plate to not move during ride and being blocked by the handlebar top mount.