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

This replacement cartridge holder is made from 3/4 inch PVC pipe and standard fittings. You will need a short length of 3/4 inch PVC pipe, a 3/4 inch female threaded coupler, a 3/4 inch round end cap and PVC cement. You will also need a hacksaw or other tool to cut the PVC pipe. Finally, an electric drill with a 5/16 inch bit can be helpful.

Step 2: Measure and Cut

Line up the end caps so they are the same length as your cartridge holder (In mine, that's 3.5 inches long).
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

Apply PVC solvent cement per instructions. You don't need much.

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

Here's a cutaway view. Let the cement dry and cure for a bit. Maybe an hour.

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.