These connect two parts together by sliding the keyed piece into the slot on the other piece until the overlapping edges snap over the ends, providing a secure connection. The variables given to the modules let you easily resize the connectors in length, width, and depth, as well as change the dimensions of the key, making it stronger in certain directions if needed, or preventing incompatible versions of a design from being connected.
If you make one or use these files, please give me feedback! I'm currently without electronics for my Prusa so I can't test and revise the fit yet. Probably nothing that can't be fixed during cleanup with a file or a heatgun.
EDIT: I have made a "flush fit" version with the locking tabs recessed into the part. With this version, the x, y, z dimensions specified are the maximum outer dimensions. The tradeoff is that the bit reinforcing the key from twisting is thinner. EDIT EDIT: The flush fit .stl and .scad now have the male connector rotated so it prints without impossible overhangs.
The x, y, and z parameters are the outer dimensions of the whole connector. The key_x, key_y, and key_z parameters are the dimensions of the key, with the exception that key_y has a y_overlap added to the key to give it a secure base where it meets the mounting block, and a matching cutout on the female connector. The y_overlap formula could be increased to create a stronger attachment to the key if the connectors need to hold under more force. I just chose values that didn't create overly thin looking pieces.