I have a CNC 3018 variant by Sainsmart called the ProVER. It does not have a lot of vertical clearance, so I wanted something with a small footprint.
I did this in OpenSCAD, so you can change a few things if you need to. I attached a script that I have been using in cncjs. It will set the X, Y and Z working zeros. You can just do the Z if you want.
I have another model that uses aluminum tape, and it works pretty well, but sometimes the tape gets gouged when i forget to connect both alligator clips. I wanted something a little more durable.
I got pretty consistent thickness readings, maybe +/- 0.02 mm. It is a bit tricky to get the aluminum sheeting to adhere well during the gluing process. I used several clamps and small blocks of wood. A more forgiving cut at the corner would have helped.
I pushed a thumb tack through the screw hole after I glued it and gradually enlarged that hole with small screws and a nail until I could fit an M3 screw in there. I put a paper clip on it so I can clip to it with an alligator clip. A couple of lengths of some thin wire, maybe 22 gauge, and a JST connector for your control board (or whatever your board uses), two alligator clips and you're done.
Initially, I used epoxy but this did not work for some reason. I used superglue and it worked much better. I bent the metal on a block of wood around the curved edge of the model before I attempted to glue it, and I had the clamps ready to go for immediate use afterward.
I haven't seen one of these corner probes go for less than $40 U.S. dollars. Certainly those are better, but this is pretty cheap and is fun to make. I can't really get closer than 0.01 mm in resolution with my machine anyway.
Your mileage may vary.
You can edit the file directly in OpenSCAD with the Customizer (on top Menu) or by just changing the parameters at the top of the file. Render the design <F6> and export to your slicer.
The author marked this model as their own original creation.