The other day I thought I could make a test tube holder like I've done many of years ago. And I did some digging and found the instructions again.
Here is what I did:
The original pattern was created by Lisa Somerville I think in 2008... Here is a sketch that will help you:
cut circle with 1/2” circle punch (or larger if your test tubes are bigger. The ones I used were from the Paper Pumpkin kit)
sides are scored 1-1/4”