drywall lift plans

Having borrowed a friend's "PanelLift", that seems to be the industry standard, I can say it is a nice bit of engineering. Nevermind doing the engineering yourself, just fabricating one with all the same features would easily take a week's focused effort.
There's about a dozen clever details, most of which you wouldn't miss for something that doesn't need to be as portable (or shippable), or work as close to a wall, or handle 16' sheets as easily.
If your time is worth anything, I suggest renting one for a day (or studying one at the H.D. rental center!) and copying what you can. It's mostly standard shapes except for the telescoping triangular sections (which I wouldn't bother duplicating).
I picked up a 41" pneumatic cylinder with the idea of making a simple lift to get from ~ 6' to 10' (i.e. the hard part), then learned this friend owned one already. I figured the cylinder would save a lot of time over the cantilevered wire rope and pulley business.
If you are interested in the cylinder, I'd sell it for what I paid, $75 plus about $30 for UPS. It's a pneumatic / light hydraulic cylinder (rated 750 psi), 41" stroke, 2" bore, 1" rod, end threaded 3/4"-16, in NOS condition. The "simple" plan was to just stick a tilting frame on the rod end and use the 41" stroke. (Lift and hang the panel with the bottom edge ~ 3-1/2' from the ceiling, then power the rest of the way and hold while you fasten.) More ambitious was a separate telescoping tube with a 1:2 wire rope setup for an 82" lift, but I figured there was no point going through all that extra trouble. 2" bore gets you ~ 300 lbs lift with 100 psi in at a 1:1 ratio.
Bob

If you need that article, I've got that issue, could scan and send. Gary Brady Austin, TX