Thanks to Zack Freedman for the awesome Gridfinity concept. I remade it in SolidWorks for easy configuring. Just use the equations to change the x and y size, and the depth to move the main extrusion down. then add your features for whatever you're making.
If you use this template, please post as a remix, so we can keep track of all the Gridfinity accessories!
Changelog:
4/19/22 - Added Non-Stackable version and example ratchet holder.
Credit Zack Freedman:
The author hasn't provided the model origin yet.