I bought some "ProGo" 280 Size Quad frame parts from RCTESTFLIGHT a couple of years ago and have found them really great for experimenting. The frame has evolved into this 7 inch frame with TBS 7 inch arms and an adjustable camera mount from ShenDrones. Currently, I'm trying to get the autonomous features to work with iNav. The aluminum "bridge" is an attempt to get the GPS/compass above EM interference (with maybe some shielding?).