Much like water has levels it can be at, I thought it would be interesting if you could cut stone to certain levels as well. Measuring the amount of free spacewould go from bottom to top, that is to say the open part of the stone would start at the bottom at 1/7 and go upwards, though maybe another setting could be implemented to cut out the top of the block instead, and perhaps use -1/7, -2/7, ect.
The measurements would be similar to water.
0/7 a wall
1/7 a small opening at the bottom, usually used for drainage. Can't be passed through.
2/7 a crawlspace barley big enough for a dwarven child or dwarf with "thin" modifier
3/7 Dwarfs must crawl to get through
4/7 Dwarven children can walk here uncomfortably, adults must crawl
5/7 Dwarven Children more comfortable here, adults uncomfortable.
6/7 a low ceiling, makes adult dwarfs uncomfortable over time but faster to mine out
7/7 fully mined out
and just for fun, the top to bottom blocks
0/7 a wall
-1/7 a small opening at the top, allows air to ventilate.
-2/7 A opening at the top, perhaps used to feed items through. same comfort effect as a 2/7 wall when gotten on top of.
-3/7 A short wall dwarfs can poke their heads over. same comfort effect as a 3/7 wall when gotten on top of.
-4/7 A shorter wall dwarfs can use as cover by getting down behind. same comfort effect as a 4/7 opening when stood on.
-5/7 A small wall that slows or trips characters moving at high speed who have legs and can't fly. same comfort effect as a 5/7 opening.
-6/7 a small prostitution out of the ground. Useful for keeping low amounts of water in one place for farming. same comfort effect as a 6/7 opening.
7/7 a fully mined out block
All the -x/7 blocks can also be used to drain a water to a specific level.