How to build....
 

home-made pneumatics? Probably not a good idea unless you have a very nice machine shop at your disposal. Tollerances in the air operation cylinders are near 0.

Air Op. gear
 

Have done a little work on air cyl. and such in the Const. business 35 yrs. 1) how do you propose to provide the air pressure? 2) you would have to make your own seals and cups 3) what type of dampening system do you intend to use? 4) how about shocks? 5) the easiest part would be to make a spring loaded cam-over set-up and use the door cover as a lock. But I've never attempted one so what do I know.