Kicad files to make a custom Teensy 3.5 or 3.6, based on the official Teensy schematics, but exposing all pins for testing. Does not route the second USB port and the SD. Using the commonly available LM1117-3.3 for voltage and a cheap USB Type C receptacle rather than USB Micro connector. Don't forget that you'll need to buy the MKL02Z32VFG4 from PJRC for this to work.
I used this as a base board for a test I did for a customer and it worked out great. All the 64 pins are tested with low speed signals & do work. You can see a picture of the customer board in the "img" folder. This was my first BGA layout. Quite happy that it worked so well!