Ever lost a Tamiya X5 or V5 spring cup (like on Tamiya TT-02B or DT-03)? I know I did. A lot. They are cheap and easy to come by, but it's so annoying to wait for the delivery...so why not making them yourself?
And now the cool thing: You won't ever loose them again - thanks to Roland's great idea - we use a screw to secure the cup!
It's customizable, if f.e. you want make them fit other chassis/dampers/shocks.
The STLs with screws use a M2 screw.