If you don't need it to be coolant proof, they are pretty easy to design. The probe and tool setter are just simple switches, that open or close upon contact.
If interested, I can post a few links to some DIY probes, that would show you how to do the setter the same way, if not easier.
There is also a cheap one that you can buy for around $140 or so that is both a probe and a tool setter combined, but you would need to swap out the connector to work with Tormach, but Tormach sells the male connector for a few bucks, so some simple connections and you'd be done.
I THINK the tormach tool setter is coolant proof, so people use it as a part of their ATC setup to touch off their tools before using them, if this is your goal, you may need a coolant safe one.