Projectile Launcher for Physics Class
It launches a projectile consistently. Pull back, hold the tail, line it up, and release. Print using a light colored filament to be able to write measurements on the sides.
I use https://a.co/d/1lBrvpR These #4 thread rolling screws (Torx T10 driver needed).
You will need small rubber bands like these: https://a.co/d/hvP9giv
Then, just print and shoot. The V shaped slot and head adapt to several different projectile sizes and keeps it centered while shooting.
Feel free to design a constant initial height pivot that would allow you to launch at different angles while keeping the launch position the same.