Well a perfect vacuum is 14.7 p.s.i. @ sea level. Easy math area x pressure = force.
Flat surfaces aren't the best to handle forces generated by fluid pressure. The pressure will cause a lot of movement at geometric transition points and they will eventually fatigue and fail. Aluminum has...
Off the top of my head from the info on your post that precision or torque aren't critical but holding is just use a 90 or 180 servo with a 4 or 2:1 speed increaser. (the opposite of a reducer) . Bear in mind you will lose torque proportionally to the change in speed plus some inefficiencies in...
I'm an ex industrial designer with 5 patents who's now a college prof. I won a national award for innovation on one of the patents in 1994. I have a few atlas shrugged stories of my own, and if you heard them you'd know why I abandoned a corporation I'd created that had successfully completed...