Square Cuvette Adaptor for Spectronic 20D

The Spectronic 20D is a visible-range spectrometer using for measuring absorbance of solutions. By now I suppose this model is a little out of date, so you can pick up a used but functional one for pretty cheap. Mine was setup for the older round test tubes, not my square 1-cm cuvettes but this adapter fixed that problem. I made my own when I found out the commercially available (but still plastic) version of this sells for more than what I bought the whole spectrometer for on eBay. 3D printing to the rescue. Works just fine on my unit.
I did the design online in OnShape, so you can go there if you want to play with it. "Spec20D-sample-holder" https://cad.onshape.com/documents/208b2636c90ef49cae776303/w/84524530acf7507fd8600aea/e/6a80fb5830493da518d2919c