Push Stick - Safety first!
This is a push stick for use with table saws, routers and other tools. Use the push stick to prevent injuries.
Remember... better safe than sorry ;).
There a two versions available. The simple one is easy to print and shouldn't be a challenge for any 3d printer. The complex version is smoother to touch but depending on your printer it might be difficult to print.
There is a normal version and a smaller version which should fit printers like the Ultimaker.