Tilapia | A Shell fed repeating foam blaster

You can grab a set of orings and cord from OOD

Update 21.3.26: Frame B exported upside down for some reason, please flip it if you downloaded it on day one (youll probably see it its massive overhangs) it is fixed now, thanks to the bug reports

23.3.26: Fixed the #016 Bolt not fitting, preventing a full prime. apologies, this error was from some legacy parts.

29.3.26 Added a chamfer to the inside of the plungertubes to prevent breaking at the transitionpoint, made the recess for the #016 oring version a little more shallow to make the oring stick out more

13.4.2026 Added a different version of the #016 Bolt, now with a completely new oring geometry without bridging and with a relatively good retention with the ring still sticking out reasonably. give it a try if you had issues with that part! (Name is #016OringBoltMK2 in the optional folder)

This uses Sillyshells, get them here: https://www.printables.com/model/880038-silly-shells-for-homemade-nerf-blasters

Thanks to sillybutts for creating the sillyshell ecosystem!

The intended and most polished build is the long version, which is the one that is unpacked on printables. it is just 3cm longer in normal frame size and performs vastly better, please for your sanity (and mine) build the long version.

Overview:

• Super Low hardware requirements

• Optional TPU seals for those who can print it

• Sleek String routing for lots of power in a small package

• High tunability

• Magazine compatible with shells that dont stick out, for full length MXL or Mega either single load or build an urchin.

• Cool shell ejection

• Liners for the bolt travel to dampen print rubbing

Printing and hardware:

• 3 Walls 20% infill for color A and color B, 3 Walls and 20% infill for color C, 6 Walls and 20% infill for color C but in the other folder. This is also noted down in the folder names.

• No support required

• 180mm³ Printer needed

• 4mm elastic string required (this stuff) , About 1,60m to tie all the knots properly

• Optional: 2 #123 orings and one #016 oring to not have to fuss with rope seals. If you can get them i highly recommend giving it a shot, they work great!

• Roughly 1273g of filament needed.

Showoff:

Assembly guide:

Assembly guide for the short version (you can find the files in the .zip, but i really dont recommend building it!):