It took me a couple of prints before I landed on the current design. To make it you obviously need a 3d printer, and in addition some hardware;

• end stop switch
• LM8UU bearing
• 8mm spring
• 6mm bolt (minimum 40mm length)
• I also thought about using a 8mm steel rod for the main part going through the bearing but ended up using a 3D printed part instead.

With some rough calculation this probe tool costed me a couple of dollars - max 3 if I also include the 2 failed design prints of the probe tool ☺

The cool thing about this design is that you can perform probing of an uneven surface thus enabling CNC jobs such as cutting or carving to follow the curves of the workpiece. Other probing tools depend on having electric conductive surface tape (e.g aluminium) on the workpiece - this is not needed with the probe tool since it uses a switch instead.

You can read all about the project here: http://diygarageprojects.blogspot.no/2017/03/3d-printed-probe-tool-for-cnc-machine.html