I take the Eli Lilly Direct Zepbound with the 0.5 ml Vials And 1 ml Syringe. I have a tremor and I broke 2 needles and wasted a half-vial of juice (ouch, expensive). My daughter has no tremor but she uses it also.

The vial snaps in securely and the syringe slides in snug enough that no latching was needed. It should be obvious how to use it.

I designed it in FreeCad and I've enclosed the FreeCad file although I have no idea why one would want to edit it. The 3mf file is ready for the slicer. I happened to be running a freshly installed PrusaSlicer. I installed it with my MK3S chosen, loaded the 3mf, flipped it on it's side, and sent it to the printer using all defaults. It came out better than I expected.