Applying Polycrylic is like trying to paint with water. It cleans up very nicely, but drips and runs were common when using a nice brush. What ended up working better for me was those fifty-cent foam brushes. My routine was 220 grit, wipe clean, apply poly, 320 grit, wipe clean, apply poly, etc. until you had 3-4 coats of poly.
My two pucker moments both involved the door. I practiced with the Forster bit on a piece of scrap plywood, making sure the door would line up. All the hardware was scavenged, and the Blum hinges I used were full-conceal frameless and my box is framed with a one-inch reveal on the sides, so I modified the hinges to work. Anyway, I had the tip punch through on my practice piece, so I was afraid of doing that to my finished door. I'd check every few revolutions with the hinge to see if it was deep enough.
Then, when I got the hinges installed on the door, I attached it to the cabinet box - and it was off by a good quarter inch! I had visions of relocating the hinges and drilling the 35mm holes again, when I remembered that I swapped hinges. Sure enough, there's a side-to-side adjustment screw that, actually, has a wide range. I was able to center the door under the drawer.
Anyway, the best advice I read when making your first couple practice cabinets is to make one, then another. That way, you don't make repeat mistakes and you get to see, twice, how certain issues manifest themselves later (or not).
Now I need to make another, then a table top to span them, creating my workbench.