We have a quite old Philips microwave where  the knob unfortunately broke. The 3d-printed one works, but I needed to drill a hole into it at the end before using it. Unfortunately I made it a little bit too long. 

In the print file there is a filament change in the file for the numbers to allow using a different colour. 

The knob is printed in three pieces to avoid supports, therefore it needs to be glued together. If you really need it, take care of the right orientation of the numbers before putting it together. 

If time allows, I'll add a more thorough redesign.