I'm drawing a water cut plan (just so that I won't need to import anything other than the delrin wheels and a few other small parts) for an OX and decided to make the 12mm spacer blocks out of two smaller 1/8" blocks stacked together instead. I was checking the OpenBuilds plan on that part for reference and it calls for two of the holes to be tapped for M5 screws. How should I tap the holes? Do I bolt the two levels together and tap them as if they were one? Do I draw them as 4.2mm holes? What happens if I use untapped 5mm holes instead?