A while ago, someone posted an instructable on a Halloween pneumatic which "popped" out of a toxic waste can. I wanted to build it, but I didn't have any of the equipment and I'm somewhat frugal so I set out to see if I would be able to replicate it with items that I already had around the house.
Step 1: Build Your Based for Piping in Compressed Air
I used 3/4 and 1/2 inch pvc pipe. I just eyeballed the sizes, although I wanted all the pieced together to fit onto a piece of plywood which would then fit into the bottom of a trash can. So you might start with measuring the bottom of your can (or box or whatever to see how large or small you need to make it.
As I said, I used items around the house - so I had a water hose splicer,
Step 2: Connect Pieces to Build Base.
As you can see, I used the 3/4 T with the 1/2 inch connector as the center. I extended each end about 5-6 inches just to stabilize the base (I anchored it down with 3/4 pipe hangers - shown later).
Step 3: Build Your Pneumatic Cylinder.
This was the really easy part for me. I just needed to know how much I wanted my prop to be lifted up and cut a piece of 3/4 inch pipe just about that length. This will house your piston and eventually connected to the base I build earlier.
Step 4: Build Your Pneumatic Piston.
Again, this was a pretty simple step. This was also left over from last year. It's 1/2 inch pvc pipe with a little duct tape at each end. At the bottom end, I just had a few wraps to expand the end a little so the air would force the piston up a little harder - you can play around with how tight you want the piston to fit within your cylinder, but you want them to move fairly freely. On mine the return was gravity driven...so I needed a looser fit. It also reduced the pressure in cylinder. To keep the piston in the cylinder, I screwed in an eye hook. In a later step - when I figured out how far I wanted my piston to extend, I tied 2 pieces of 60lb nylon string to the eye hook and attached it to the plywood base. This served to keep the piston from rotating and ensuring it didn't leave the cylinder :) Although I tested it without the string and with the manikin head attached, it barely left the cylinder.
Step 6: Connect Piston/cylinder With Base.
Step 7: Finished Pneumatic Lift
This is the lift assembled and connected to my "air hose" which is an old water hose I had..again - I used items that I had around the house. The 2nd photo shows how I released the compressed air into the hose.
Step 8: Connect to Air Tank/air Compressor.
I don't have a fancy air compressor - I have a pretty basic one that you can adjust to how many pounds you want. I have mine set to 40 lbs psi and I have that attached to a small portable air canister. This is connected to my blower - below - which I then have connected to my air hose.
Step 9: Pneumatic Lift Inside Trash Can.
AS you can see, it fits pretty snug - it lifts right now - I have a hole drilled in the side of the can to attach the air hose and you can now see the 60 lb nylon string. The 2 pieces of nylon also limits the twisting that occurred with only 1 piece.
Step 10: Have Beautiful Assistant Attached Test Dummy
My Halloween assistants attached a test dummy to see if the lift actually worked.
Step 11: Testing the Lift
Step 12: Final Step - Can the Assistants Look and Act Scared?
Step 13: Finshed
This took about 30 minutes to build. I built another smaller one to move CAD BANE which will be run off the same air hose (i'll use a y splitter which I will have to buy). The pressure is not much at all - there is enough air leaking around the piston that it just lifts the full head with wig, and lid. It does look like there is also enough air to give cad bane a good little bump so that he lurches forward a little bit as well. So far, I keep the air compressor set at about 40 lbs and it seems to work well.