Originally Posted by miltimj
From what I've seen, most projectors do not vent heat out the bottom of the projector, so the plexiglas isn't an issue. What PJ do you have (or will you be getting)? If you already have it, notice where it vents, and if not directly off the bottom, this mount won't be a problem.
Although most projectors do not vent heat out of the bottom, heat does rise. However, the fan should blow much out that out of the vent. I built a similar mount for my X1 a couple years ago. Although you can't see it very well in the picture, I mounted the plexiglas as high above the PJ as I could. This was done by finding the longest bolts that fit into the PJ chassis, I believe that they were about 3 inches in length. I then used metal tubing as spacers to cover the actual bolts. The goal was to keep heat from building up between the PJ and the plexiglas by providing more ventilation volume. I don't know how much it effects the heat build up. One benefit is that it also provided a greater "drop" from my high ceiling so I could position the PJ without using any keystone correction.
The PJ is mounted to the ceiling using a speaker mount, which allows for some adjustments for leveling and positioning. The speaker mount was extended by using threaded rod and covering it with metal tubing. This gave a thinner, sleeker look than larger metal pipe. I've seen some great looking mounts that use larger metal pipe which also allows cables to be hidden. I decided against this since I prefer to keep my video cables away from power cables so they won't pick up any "noise". Aesthetically, some people like to hide their cables, some like to have them visible. I respect both opinions (as I've seen great looking mounts done both ways) but prefer mine out in the open especially if they are "dressed up" with techflex and heatshrink.