Test Tube Rack MK2

thingiverse

This is a rack designed to hold 10 test tubes. Mine measures 19.8mm outer diameter, and a 20mm diameter would probably fit as well. The Fusion360 source file is included, allowing you to modify it according to your needs. A user parameter for tube diameter has been incorporated, making it easy to adjust the rack for different tube sizes. To ensure smooth insertion of test tubes, I recommend setting this parameter about 0.5-1.0mm larger than the actual measured diameter.