FTDI is Great!
But header pins can get in the way of your next tiny project. For the benefits of FTDI, without the bulk of header pins, Fiddy comes to the rescue.
Using a spring, pogo pins, and a extreme optimism, Fiddy chomps down on the headers on your Pro Trinket, delivers and receives the debugging and programming information you need, and then speeds off to a glorious life once finished.
Check out the full tutorial at https://learn.adafruit.com/fiddy-ftdi-pogo-pin-clip/