Parametric Hex Key Holder

Inspired by https://www.printables.com/model/1118458-hex-key-holder/files, a parametric wrench holder.

For metric, just set wrench_sizes to be the list of sizes you have.

For SAE or Torx sizes, set wrench_sizes to be the list of sizes converted to mm, and set wrench_label_overrides to be the name you want to see.

french_cleat_depth will add a French cleat of that size in mm to the back of the holder. 

screw_mount = true will add a flange with space for two #8 screws to either side of the holder.

label_depth allows you to set the height or emboss depth for the labels. Set to 0 if you don't want labels.