Summary

This rubber band gun has the frame as a single piece and can load multiple shots. The "sight" is separate so it can be printed in a different color -- when I do it again the sight will be in glow in the dark.
This is based on the "Rubber band gun simi[sic] auto" with changes as follows:

frame joined as single piece
pin/dowel tapered to ease insertion
front sight separate piece
trigger guard expanded to accomodate trigger
grip is taller

Instructions

Printed all parts at 0.3mm layer height for speed. Although it is designed to grip, the sight/frame snap in works better with layer texturing anyway. The pins also gain a friction benefit. The other parts are unaffected so there is no real reason to print at high resolution.

Mostly printed with 2 shells and 10% fill, though I think I increased that to 3 shells and 15% fill on the front sight.

Assembly is pretty straightforward: the trigger and sear can only be fitted to the block and pinned in a single way. I then put the wheel in and pin it. The sight is just pressed down into the gun frame. No glue needed though it could be used on the pins and the sight.

If my revised pin is too loose then use the one from the original, but I found the results on my replicator 2 to be too tight to work.

Given the particulars of this design, I could only get four bands loaded. If it doesn't fire on the first trigger pull, pull again and it will.

If you have problems with the action being too stiff you can print the Mk3 pin and use it instead. It has been modeled for a slightly looser fit in the middle to reduce binding.

One-Piece Rubber Band Gun