A friend of mine working in a lab was in need of a design for some coverslips as she couldn't find anything suitable online, so I came up with this: https://www.printables.com/model/311384-coverslip-box/files

Same friend has now come to me asking for a solution to wash these same coverslips. Apparently they need washed with an acid solution and after discussing the best way to approach the design, this was the end result after a couple tries in Fusion 360!

I haven't printed it myself as she is 3 countries away from me and an STL is a lot easier to send. Instead, she printed it at her university 3D printer in ABS, to account for chemical resistance.

You might be able to print this without supports on the handle, depending how well tuned your printer is but I would advise to use supports for the handle. Especially now that we have organic supports on the latest alpha release of Prusa Slicer, which are ABSOLUTELY AMAZING!