RPI3-dat
look

Pin Definitions

Version 1 from MPC1111-dat

CAD version
STL or solidworks - https://grabcad.com/library/raspberry-pi-3-reference-design-model-b-rpi-raspberrypi-raspberry-pi-1
mechanical drawings - https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#raspberry-pi-3-model-b