More often than not when in a lab, you will need to use various sizes of different kinds of tubes when performing an experiment. A classic staple in any lab is a rack for holding multipple specimens, and one that has multiple options for sizing is a convenient must-have.
These simple pieces pf lab equiplment can run $10 or more depending on the distributer, but the 3D-printed equivalent is just as good but significantly cheaper.
This one was designed based on the one found below, which costs about $15 each. These racks cost about $2 to print in PLA