I broke the cartridge holder of my Ultraflate CO2 bicycle pump by stepping on it. This instructable shows how to make a new one using standard 3/4 inch PVC pipe and fittings.
Step 1: What You Will Need
Step 2: Measure and Cut
Notice that these PVC fittings have a small ridge inside them, which is a dead-stop for the 3/4 inch PVC pipe to slip to when it's assembled. While the PVC pipe won't reach the dead stop in a dry-fit, it will get there when you add the solvent cement, which temporarily lubricates it.
Take the dead stop into account to cut a short length of PVC pipe to fit between the two end caps.
Step 3: Assemble the Parts
Push/twist the end caps onto your cut 3/4 inch pipe until it is completely seated, and the assembly is the correct length.
*** Note *** You'll only have a few seconds to do this. Make it a smooth motion. Often it is a good idea to mark your PVC pipe to show how far it is expected to go.
Step 4: The Fully-assembled Piece
Step 5: Special Feature: Drill a Hole
To let you store a CO2 cylinder inside the holder, it's good to drill a hole into the end of the rounded cap. My BB gun style cartridges have a neck that's about 1/4 inch in diameter, so I drilled a 5/16 hole in the center of the rounded cap.
I may the only person who is clumsy enough to break their Ultraflate bike pump in this way, but now I know how to fix one.