I use a pedestal mount for my downstairs room. The pedestal is a modified Peerless ceiling 3' tube mount. I installed (weld) a couple of angle iron clips so that it could be bolted to the wall. The mount came with what looked like a foot so I used that on the bottom. My projector is heavy, nearly 30 pounds and with the shelf and inner tube the total weight of the sliding assembly is 40 pounds. I installed two 40 pound (stacked) gas air springs so that I can raise and lower the whole assembly using two fingers. The mount was left over from a school project that I built and came as a complete kit. The kit came with brackets for mounting a projector, TV and a DVD/VCR player. I looked and did not find the kit, but here are some of the pieces (or similar) that I used.
Peerless tube with extension www.peerlessmounts.com/dyn/Products/BrowseProduct.aspx/sp/560
Ceiling plate that I used as base plate www.peerlessmounts.com/dyn/Products/BrowseProduct.aspx/sp/612
With all of the hardware that came with the mount there was a threaded collar with set screws. I took a metal plate and weld it to the collar. Then I screwed the plate to a piece of MDF to make the shelf. Collar is then threaded onto the inner tube and locked in place with the set screws.
You can buy this whole assembly and use it. Just fasten a shelf to the projector mount an set the projector on the shelf. This way you can level the shelf using the projector mount.www.peerlessmounts.com/dyn/Products/BrowseProduct.aspx/tn/317/u/t/categoryID/193#optional_accessories
Here is a picture of the projector is the raised (not full height) position.
Here is a picture with it fully lowered.
Side view of it raised.
As you can see this is a challenging room for a projector. This end of the room was built for HT, but I built the room back in 1999 for direct view and the room is also a family room so it has lots of windows. In 1999 I never even thought of using a projector. Projectors were too expensive in 1999 for me to even consider.