For this, you'll need
- 20mm PVC Coupler
- 20mm Conduit Coupler
- Barrel of any Nerf gun (I used AT)
First, start wrapping e-tape around the ends of the barrels like so.
Getting a good fit will be trial and error, now you can start fitting the couplers on.
And Tadah, done! all you need now is a method of mounting it, and maybe some paint.