6" Rack, RPi3B - Tabs, Vented, No Screw

I remixed the Pi3 case for 6" racks. I had 2 goals:

1. Tabs to hold the Pi3B instead of screws
2. Vented on the sides to provide more air circulation. I'm going to put a fan on the side of the 6" Rack to cool multiple Pi3Bs concurrently.

I've printed 4 of these and the Pi3B fits nice and snug. You have to slide it in carefully, but it fits and there isn't much wiggle room.