Base for AUER Toolbox Pro

This is a latching base to attach a [Toolbox Pro from AUER](https://www.auer-packaging.com/de/en/Tool-boxes-Pro.html?customer_type=private) to a 40x30cm² base plate.

I was printing the cavity/bridge without any support. The way it came out isn't beautiful but it works out-of the box without cleaning or anything.

Print the "left" mounting piece twice, print two "right" ones (just mirror the "left" ones in your slicer) and print the "center" piece once. → Done.