This tool holder is designed for the iGauging machinist square set, but probably works for any similar sets from other manufacturers:
https://www.rockler.com/igaging-3-piece-engineers-square-set
A left and right version are provided as STL's depending on which way you want to be able to slide them out from.
Should you have a different set, an Inventor file is provided and can be adjusted by modifying the parameters.
Each size (large/medium/small) has a depth, length, blade width and blade thickness. Here is a diagram on how each one is measured:
No supports needed. Print at .16 layer height and oriented with the shelf on the build plate:
The author hasn't provided the model origin yet.