Just a minor update: I installed the pots and marked the size and shape of the recesses I have to make, because the shafts of the pot are not long enough to fit around the top and pickguard together. I first wanted to use a smaller forstner bit to drill out the desired shapes, but I figured the center point of the bit would then go through the entire top (which is 6 mm thick, I need a recess of at least 3 mm and the center point of the forstner bit also protrudes 3 mm). So I figured I’d better use a Dremel or a router. Alas, the Dremel was unable to reach the desired depth (I need the depth of the control cavity plus the 3 mm I want to remove) and the router just reaches the desired depth but would cover up the entire cavity, making it impossible for me to see what I’m doing… so I made some measurements and now I think a 25 mm forstner bit would remove just enough material, while I still could locate the center point inside the hole the pot goes through, to prevent drilling holes in my top around that hole. I’ll stop by the hobby store tomorrow, I hope I can find one.
After this rather time consuming adventure with no result, I only managed to do this today, but at least it’s something: