Made this part to replace a broken cap on our attic ladder. It's one of my earlier Onshape designs and thought I might share it with the rest of the world.

The current replacement cap, printed in black PLA, has held up for 6 months by now with no issues :-D

If it doesn't quite fit, create a remix and upload it to help others!
I've shared the measurements as well as the STEP file to allow for easy customization, the default hole is designed to fit a M5 bolt to secure it to the ladder.
 

Note for printing: Make sure to print with decent infill percentage (>20%) and at least 3 parameters to ensure the best strength!!