Test tube stand

A simple test tube holder (test tube rack, test tube holder or whatever :)

Holds four test tubes and has a wide base for stability.

Prints without supports on its side (see picture). At 100%, the inscribed circle of the hexagonal holes is exactly 15 mm in diameter, so measure your test tubes, add some clearance (ca 0.5–0.7 mm) and scale the model to achieve this target dimension. If your bridges tend to sag or you get your Z dimension squished a little (which the model as it is does not account for), you can compensate for it by using a slightly larger scale in Z than in X and Y.

I printed with PLA for nice bridges, but it's not good if your test tubes are going to be hot, so consider other materials if that's your case.