Remixed from the original as the holes were slightly too small for my test tubes (ones with the little flip over cap) so I made the holes a little bigger and added anther holder so it can hold all my Master kit test tubes + my KH and GH tubes at the same time.

It's not perfect and could use some future refining. I would make the gap between test tubes bigger and between the tubes and the card bigger too.

I recommend flipping onto its side for easier printing.