Here are some picture of the wheel building jig I recently made, Mk1 was just holes drilled in ply board for the centre spindle and rim supports. This one mk2 is adjustable and rotates on thrust bearings.
Setting up on the wheel before I tear it down to get the hub powder coated
Large square washers welded to some nuts allow me to set the dish of the rim to the hub, bolts slide in the slots to give me 17" to 21" rim capacity, I built up 2 flats of the bolt head and filed so it slides inside the 1" square tube but cant rotate.
Mounts in a vice to keep fairly compact
Used some old thrust bearings I had so the jig spins freely so I have easy 360 degree access to lace up and tension the spokes.
I do the final trueing up on the bike in the swinging are or forks.