Lucky for you we have Set Focus now, so you don’t have to do math! The thing to remember is that it only cuts/engraves in that 1/2" range, so when you take the tray out your item needs to be elevated enough for its top to be higher than where the top of the tray would have been. That’s where things like these jigs come in handy.
Been engraving wood bar taps for a customer for over a year. Hundreds. 1-3/4" thick maple, triangular. Engraved on all 3 sides. Paid for my GF Pro with that one customer. Now I just have them run me a Craft Beer credit instead of cash. I’m happier that way.
Made a jig. I do three at a time and flip them. Usually different beer names and brewery logos for the taps. I only do three because I can’t afford to waste the taps if something goes wrong. Never has. Probably enough room in the GF to do 6 at a time.