There are several macros around on this forum, and I have concocted my own based on one of them. Basically you set the tool over the "height finder" which is 38.84 mm high, touch the screen button for auto tool zero, the tool lowers itself gently until it touches the finder button, then lifts up to 50.00mm above the table.
As regards the touch plate itself, rather than a plate I have made a spring-loaded touch-off button which sticks to the bed with a magnet. The advantage of this is that if the touch isn't sensed for some reason (for example I have been known to forget to connect the probe input!) the tool doesn't crash and you get at least a chance to hit E-stop before it's too late. I didn't produce proper drawings but could post some photos if of interest to show how it's made.
I've also made a spindle probe with an isolated concentric tip 10mm dia (well, 9.97) that I can use to probe to set up X and Y edges. There is new code for the edge finder buttons in the offsets screen.
These features together make setting the machine datum a breeze.
John.