This is a piston with a cap too put your finger onto, then you can just have fun with it.
You can also screw the piston to any surface you want, this way you can attach anything to it with a M4 screw.
To build it, you'll need :
For my prints I used an ender 3 pro with a 0.4mm nozzle. I had a little problem with the cap but a little bit of tuning and it should be fine !
The author hasn't provided the model origin yet.