Having tried the craft once, I now have some tips for you. Here's how my first attempt went.
1. Not enough holes, not enough mice.
I hesitated to cut too many holes to begin with, because my test pumpkin was so small, but now that I see how it looks with too few, I will know better next time. More holes. More holes, my friends.
2. There's not enough variation in hole size.
I made my holes using a regular paring knife. I cut out diamond shapes first (which was easy) then rounded them out with more careful shaving. Doing it this way meant going to a pretty large hole size each time in order to get a uniform circle. I think this project would look better with some smaller holes mixed in. Small enough for just a mouse snout or nail, you know? So next time, more holes, and more variation in hole diameter.
3. The mice wouldn't stay in place very well.
This was annoying, but easy enough to fix. I resorted to pinning them down. You can clearly see the black round pearl head of one of the pins I used in the first shot (centre mouse). It's what I had handy. I'll have to hunt around for more subtle-looking pins in my sewing kit, but regardless, pins are, I think, a necessity. That's just a pro-tip for y'all.
Anyhoooooo. I just wanted to update you. Halloween is still a couple of weeks away, so I know I have plenty of time to get this right.
You know, this is the first year I ever tested out a pumpkin decoration before Halloween night. It's nice to have some breathing room. Most years, I find myself rushing home from work, swinging by the grocery store on the way, grabbing whatever mangled pumpkin is left and hurriedly carving it as fast as possible, into whatever stupid face I can manage in 30 minutes or less. Next thing you know, kids are at the door and I have a bunch of cuts on my hands, and pumpkin guts everywhere, giving me a rash on my forearms. It always so rushed and unpleasant. This feels much better. I mean, I still messed up and burned the pumpkin seeds, but that's just me. Spaz to the end.