PX4 supports numerous types of single- and multi-copters, including helicopters, tricopters, quadcopters, hexarotors, dodecarotors etc, in many different geometries (+, wide, x etc.). The complete set of supported configurations can be seen in Airframes Reference > Copter.
This section contains build logs/instructions for assembling and configuring a number of copter frames.
DJI Flame Wheel 450 with Distance Sensor and RTK GPS (Pixhawk 3 Pro)
Lumenier QAV250 Pixhawk Mini Build
DJI Matrice 100 (Pixhawk 1)
QAV-R 5" KISS ESC Racer (Pixracer)