Nerf Rainbow Derringer

This is a rainbow-style catch Nerf homemade blaster using 1-inch 200 psi PVC as the plunger tube. It's quite small, but is a lot of fun. Not the easiest build out there, but very far from difficult! Included are options for a single front-loading barrel, a triple forward-facing barrel, and a triple barrel duck's foot (which is hilarious, surprisingly functional, but mayyyyy lack any practical utility). Also included is a six-shot manually-rotated pepperbox front end, which is probably the most useful if you intend to use this as anything but a single-shot backup.

The plunger head, catch, and T-pull should be printed at 100 percent infill.

You will need:
1-inch 200 psi PVC, cut to however long you wish your plunger tube to be.
1/4 inch rod (I used aluminum rod from Ace Hardware) cut to match.
A mainspring (I'm using 4 inches of k25)
A catchspring (a strong pen spring, or something similar. I got mine at Ace Hardware, can't recall the number.
An o-ring (not sure what size I'm