1:1 scale AR15 style semi auto Rubber band gun
printing, assembly, function in youtube video

Materials needed for assembly

• M4x20mm bolt : 12ea
• M4 nut : 8ea
• 7x12mm spring : 4ea
• 3x10mm spring : 1ea (or something similar to ar15 selector detent spring)
• a rubber band
  (it's a recommendation, just use anything that fits)

70x1.5mm(common one) and 70x3mm band will both work
70x3mm will work better and is more powerful
but i only tested it up to 5 rounds
70x1.5mm will sometimes jam, but 10rounds testing was ok

if you experience double fire or frequent jam,
tighten or loosen the screw holding the disconnector

Safety first
Installing a bolt at the gear axis is essential for the part strength!!
Strength of the parts will vary by the filament and printer setting,
so handle with caution

Tolerance
0.3mm or more for moving parts, 0.2mm for fixed parts
use supports

same file is also uploaded on cults
https://cults3d.com/en/3d-model/game/ar15-rubber-band-gun-mlok-customizable
if you buy my model from here, i would consider it as a support