For te past two years I wanted to build my own stand but after looking far and wide for a crank that suited my needs (thanks Hpaten and others for your input).... I decided finally to pay up and bought a sculpting stand with a hand crank - the stand adjusts from 33" to 50" and has a 24" top.
I bought the square top option instead of the round one to have more space to put my tools - now that I have used it for 2 days I find that choosing the square top was a good idea. The stand has lockable casters and can withstand 750 lbs - my bigger pieces are about 75 lbs.
The ability to move the piece up and down is a real must. Initially I used Merlion's solution (Ikea's cheap kitchen island with various props and a turntable) which is still an excellent solution for smaller pieces (see his message and pictures in this thread) but for my bigger pieces I used to climb on a stool to work on the head and crouch down to work on the feet. Now instead of focusing on the acrobatics I am more able to focus on viewing various angles from various heights.
This stand should last a life time. My studio is tiny so I took the pictures from outside.
The stand comes in 3 pieces easy to set up with basic tools, except for 2 side bars which are too hard to pull up, my husband is on a business trip so that has to wait. The packing is a bit of a mess and I had to claw at the foam to recycle the cardboard.
Two sites sell those cranks: