This is the second version of my 3D-Printable Endstop Switch, but has been redesigned to be smaller, stronger, more reliable and consistent than it's predecessor. I have successfully used this end stop switch for dozens of prints with no problems from it.
So if you want to build your own end stop switch instead of spending a few cents on one, this is for you! Join the zero-point-something percent of 3d printer owners who actually 3D printed their own end stop switches! What are you waiting for? Head to the 'instructions' tab to get started!

1. You will need some solid core wire (or craft wire) about 18 AWG in size, as well as a spring from a pen or mechanical pencil.
2. Download and print this thing. I used 2 shells with ABS, I also slowed down the speed to 20mm/sec to let the thin parts cool better.
3. The pictures really help with this: after wrapping the 'E-Stop plunger' with wire, insert it with a spring into the 'E-Stop body'. Next add the plunger, and then run two wires through the holes in the 'E-Stop body', all the way up through the 'E-Stop cover'.
4. If you want, you can glue the cover in place, and then mount the switch to your printer.
5. To recap, the two wires running through the 'body' should not connect until the 'paddle' is depressed, and the wire on the 'plunger' shorts the two wires.
6. If you need any help, ask in the comments: I'd be happy to help you.