A test tube holder designed for aquarium test kits. This is a slimmed down remix of my slim test tube with compartments. It's also a remix of kkwsiu's test tube rack, but thingiverse's remix function is currently broken so I can't add it:

https://www.thingiverse.com/thing:4638123
https://www.thingiverse.com/thing:2004484

Pictured are 16*50mm tubes - I've measured the print itself with calipers and the tube rack holes are ~16.5mm in diameter. I think this design should be compatible with NTLabs tubes but I don't have the original NTLabs tubes anymore, so please check this before you print. Standard 12*75mm tubes such as the API glass tubes will fit, but obviously they will sit loosely in the rack.

I recommend you seal the finished product in some way - a lot of 3D prints aren't watertight due to the layering, and you'll find water 'weeps' through the infill in that case.

Creality

Ender 3

No

Yes

0.2

15%

Please note that there are 80 degree overhangs on this print. My printer could handle this fine, but if your printer cannot handle this, I recommend printing with supports.