Summary

this is my change with support for microswitchs like http://hacker.instanet.net/Store/micro-switch-right-angle-p-42.html
or http://hacker.instanet.net/Store/micro-switch-extended-button-p-44.html

I took some microswitch from a toy remote control that was broken.

Instructions

You just print this, buy 3 microswitch
Add them in place with some sort of glue, if you think is needed, or double sided tape,
wire them in series so if one of them isn't clicked it will break connection.
I cut one leg of the switch, and added one into the small hole. You will need to enlarge a little bit the slot for the microswitch with a cutter, if you don't cut to much you will not need any glue.
When you mount this you will need some small springs, I took mine from some courtain holder, be creative. You can cut a spring from a pen for them. You need to put a washer on the screw, then a spring, then another washer, add the support, other washer another washer and bolt it all together.

Make sure that all switches are pressed and connect the wire to the Z-probe.
When the extruder hit the bed, the microswitch contact will be broken and z-probe will be alerted.

Initially the central hole was meant to be for the Fan wire, but I added a small led in the central hole in order to see when the contact is broken. This is not necessary, but makes thing a little easier to test.

Please note that this is my first 3d work, and I din;t have time to test yet the actual Z-probe auto bed leveling.

J-Head Bowden Delta Printer (bowden support, all metal) with microswitch