I've made my own in the past that took forever and still weren't as good. The little nubs lock into these motors and take the load off the screws. And the other side locks into the blades they sell or you can design your own with the same slots.

[FTR tip: The blade screws don't need to be cranked down; they are only there to keep the blade on the locking slots. Use threadlock so they don't vibrate out, and just snug them up a quarter turn.]