You can use these mounts to hold a set of small ESCs in place on your quad. These were made for a FeeYoung ZX-250 frame and mount the FVT LittleBee 20A ESCs. However, they may work for others. Requires glueing.. Hot glue or Goop (my favourite). Note: This is a single STL but 2 parts.

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FVT LittleBee ESCs   FeeYoung ZX-250 Carbon Fiber Frame    Tinker this thing.