This set of adapters will allow you to mount 20 x 20 stacks such as the Magnum Mini in all of my drone frames.
Takes M2 Fits to M3. Files are also included for M2.5 fit M3. Printing the insert section in a soft material like TPU will add some vibration reduction.
To secure the flight controller place into the slot on the bottom of the mounting plate and then put in the M2 screw with a washer.
You can use whatever combination be suits your print to lock the flight controller securely to the frame. You can rotate and mount the stack like a Tiny Whoop with a corner facing forward to in the regular manner by mounting through the arms.