I made a KiCad PCB template for a Raspberry Pi HAT and was encouraged by an Element14 user to share it here! The layout has the correct outline, mounting hole locations, and GPIO connector placement to mate snugly with the Raspberry Pi 3 or Pi Zero. Here's a link to the template on Dropbox! https://www.dropbox.com/s/i0olr0trd956kv9/Pi_HAT_Template.kicad_pcb?dl=0
If you found this useful, you can check out my other Raspberry Pi projects at www.youtube.com/c/EdjeElectronics ! 
