I like weird copters, so I present a 3" bone quad. Originally built with spare parts, now the only salvaged parts are the VTX and batteries.

The battery is too large for the quad, though it still has some punch; I might grab some 650 or 550's next. The eco motors are currently not pictured, but seem solid.

Getting in the air is the hardest part, you have to balance it on something to avoid striking the ground with the pusher props. Roll isn't particularly affected by the... unique force envelope of the quad, cornering definitely is, the quad is very floaty around corners. I'm drawing ~9A during punchouts so I could have gotten away with an FC with lower rated ESCs.