This Flight Controller Mount is available from Banggood.com and GoodLuckBuy.com and numerous eBay vendors; price ranges from $5-8 shipped from China.
It's made from .060" Fiberglas plate, and it comes unassembled. The holes for the grommets are a snug fit, so it holds together very well as demonstrated in my video; the slight preload on the shock bushings makes it feel very precise. It is sized to fit the ArduPilot & PixHawk; however, any of the popular flight controllers should be easily mountable.
My only warning would be that the cut edges are very sharp; I dressed the outside edges very lightly with an emery board to soften the edges so I don't cut myself.
The video cuts off abruptly due to running out of space on my card. What was missed wasn't really important; just me blathering about assembling it and I need to go make dinner, so, here it is.
mnem
So there!
