Thanks go to those who helped me out in the Yet Another Starting Discussion. I'm feeling much more confident in my DF dream.
Current status: ~30 dwarves, found the first and last cavern (I think I dug past the second without hitting it), redacted, shiny, and the magma sea. Small start on the site: Currently, I have a hexagon 36 tiles from top to bottom(north-south, just one Z-level for now) with an in-road, not yet exposed to the surface. I intend to move my dwarves from their original location to a well-planned one underneath the hourglass.
Stage 1: Basic necessities: I'm going to try to plan out just about everything my dwarves need, at least on a workshop and stockpile level, including some pipes for serving the magma furnaces and such. Since I'm going obsessive about hexagons, I'll probably have most of the rooms in that shape. I think I can just spend a day making plans for that, making sure every workshop has an appropriate stockpile nearby. Magma will be sent up by a pump stack.
Stage 2: Obsidian casting: I construct a wall around my hexagon, and build it up 2 or 3 z-levels, making extra sure there aren't any cross-corner leaks (and that the staircase I already put in is covered with a constructed floor) and pump the magma in.
Stage 3: I build part of my other mega construction, a raised aqueduct filled by pumping water from a brook and pour it into the magma, forming giant hexagon of obsidian. This will be the bottom cap of the hourglass.
Stage 4: I start constructing the hourglass out of clear glass. A temporary workshop for making glass blocks will be there for ease of access, as well as a large stockpile made specifically for clear glass. These will be removed once the glass portion is finished.
Stage 5: I create the top obsidian cap with the same casting method. Carve out expensive rooms inside for nobles, with a stockpile for high quality food and drink so that they can be happy. Right up until I arrange some form of Unfortunate Accident if they complain.
Notes:
I'm specifically thinking of the casting method, since IIRC, constructed walls aren't as valuable for rooms, and the casting method treats the obsidian as natural.
Since I only found two caverns before hitting the magma sea, and 3 is supposed to be the default, I may need to do some exploring, since I'd rather not have an unknown crop up by finding my new location an unplanned access. I may seal off a low value dwarf with food and drink in the old location and designate him a miner until he discovers the skipped second cavern... After that, I might try having fun with him as a hermit, slowly sculpting the caverns into geometric shapes and learning to live among the Crundles.
So, any suggestions, particularly for the more deeply planned workshop levels?
UPDATE: Actually, I think I've got a good enough grasp (and a powerful enough laptop) I might just start over on a 6x6 map after I figure out a good floor plan for workshop levels.