All holes are slip fit, with the exception perhaps of the mainspring pin. I tried to be clever wtih press-fits for certain holes, but its best if you just make everything a nice slip-fit with minimal play.
I found that using a exact diamter (1.5mm, 3mm, 3mm) drill bit was best, and then honing out the holes until you achieve a very free slip fit with minimal play.
It is best to look at the STL and figure out the depth of blind holes and use a depth stop collar on your drill bit. Some of the blind holes have very little material at the bottom, and it is very easy to accentally go through.
Make sure all your pins are straight, especially the longer ones from the hours/minutes transmission. I was using some quesitonably straight brass rod, and found that slight bends will result in your gears not spinning freely.
- Used #0 and #1 sheet metal screws in place of 1.5 and 1.8mm screws. Also #2 screws for the watch face.