Propeller balancer: you can build your own double printing the face part and purchasing this items:

https://hobbyking.com/en_us/simple-prop-balancer.html (€ 1.5) https://hobbyking.com/en_us/3x37mm-alu-light-weight-round-stand-red.html (€ 6)

If you don't want to buy the pipes maybe you can print them and leave a small hall inside for skew threading or buy something like this https://hobbyking.com/en_us/m3-all-thread-rod-300mm-2-pieces.html with some m3 bolts.