Step 1: Parts List
1 wire mesh pencil cup (with mesh bottom)
1 piece of 1/2" PVC pipe scrap cut to length of cup
2 medium length rubber bands
2 hose clamps
The cup cost $1 and the clamps came in a variety pack of twelve that also cost $1. The elastics came in a wonderful bag labeled "One pound of rubber bands" (also $1) that I have used for many a project. I already had the 1/2" PVC scrap laying around, but even if you buy a ten foot length it will only cost $1.50. Cutting the PVC is a real pain unless you get some ratcheting pvc cutters, which I highly recommend. PVC pipe has so many great uses (it's sometimes call "the Tinkertoys for adults") that these cutters are a wise investment. Get them for a scant $2.49 at Harbor Freight ToolsHarbor Freight Tools.
Step 2: Bottom Out
Once the bottom of the cup is removed, check the edge for straggling bits of metal that someone (like you) could cut their fingers on. Get some needle-nose pliers (I used the Gerber multitool that I always carry) and pull them off. I'm all for expending blood and sweat on a shoot, but tying up loose ends like this will save you some.