Well, I'm currently digging a tunnel to the Mountainhome's magma intake pipe (Well, oil, but...) It's been slow, and I can't progress much farther in the sweatpants I'm currently wearing, and my shovel is FAR too large. I'll need one of those tiny beach shovels, for sand castles.
I've had a cave in already in this test tunnel, from breaking up the middle ice layer (There's the ground, frozen solid, then 3 inches of powder, a layer of ice an inch thick, then a foot or so of more powder, and a top layer of ice). From now on, I need to start my excavation from the bottom, and let the ice break apart, then have all the powder fall down, off of the roof, creating the most stability.
Once I have a good area dug out, I'll go into production (Searching for) of upright spike traps (Icicles, duh), and setting them up. A problem I foresee is that for the tunnels to be stable, they need to be no wider than my shoulders, so any turning might be difficult, and turning around will be downright impossible. I plan to solve this with tunnels that circle around. Also, since getting lost is probably going to be a big problem (Everything looks the same in there), I'll make signs to tell me where I am. Light is NOT a problem, as sunlight can pierce through the top layer enough for me to see. Obviously at night this won't be true, but I'm not badass enough to spend a night in there.
Workshops might be open to the air, because that would be easier, I'll see when I get there.