Hum, built, as in designed, framed and finished several houses plus shops. Prior planning and more planning.
It ain't big enough, mine ended up 45x45 with 12' celings
Central heat and air, gas
Celing fans and 4' tube lights around the walls
Put a gas outlet outside for casting, grilling, etc.
Spray foam insulation, closed cell exterior walls and roof
A small 12" operational window with bars mounted.
90 gallon standing air compressor unit, schedule 80 pvc, QC and water filter at each point
Flake Board, painted white with a heavy knap roller, 1/4" lattice on corners, 1x4 base boards, cheaper than sheet rock.
Epoxy the floors, latex single mix, light grey. 16-18" rollers, thougher than woodpecker lips.
10' Roll up, insulated, sealing, garage door. Works for moving in a mill and lathe. Put 8' sloped ramp outside the RU door
Lay out your equipment on a to scale drawing and do the electrical and air to it.
Plan for a rotary phase converter
Hookup on exterior of the interior panel for a generator
Make room for a big safe room, you can form and pump it, reinforce the floor slab for the weight. Reinforce your clan corners the rebar across the corners.
Wire for cameras if ou want security
Use unfinished birch cabinets, upppers and lowers, I got 50 units before I was done. Put Sander sealer on them.
Work bench two 2x12, with a 1x2 between, a 2x8 as a back splash. Screwed and glued with pipe clamps. Use a belt sander to surface. Great for vices, presses, etc.
Vacuum system for wood shop area, Put a door off the return air for the AC
Rough in the plumping for a toilet, below the concrete surface. Just a stub for cold water and a flange for a toilet.
Water spicket frost proof, outside the walk in door, right in the wall for the toilet water.
I would do metal siding to match the roof. A house is rated, not an out building.
An amplifier with antenna for cel phone, due to steel roof.
Speaker wire for any music, do wire before the wall covering, 2x any plugs you think