This is my Z touch probe. It is made from 4 mm garolite (fiberglass board) and two pieces of spring steel. Pallet shipper strapping works well. One of the leaves needs to have a larger hole drilled and a plastic washer or other insulation to fill the gap. I use a normally closed loop for all my homing and probing. I also plasticoated the end of the longer leaf to make the actuation rely on the separation of the leaves and not a ground from a metal bit. (That was happening) Electrical tape works too. This gives me the ability to probe with other things besides metal bits. I have several screw on attachments that allow me to use things like; paint pens, rotary needles cutters, Roland vinyl blades and what ever else I can dream up.
I was using the flat plate with a alligator clip on the tool method. I was having problems with electrical noise causing false positives. I decided to go all normally closed with capacitive filters to dampen the noise.
I works really well and is very accurate. I decided to use sketchup picts because it was easier to see how to build it.