I figured I would use a lot of rubber grommets (Lowes, automotive section) and rubber washers throughout to limit any vibrations...
I ended up spending about $70 on supplies, but I'll probably return the spray paint and some extra washers and such.
I had Lowes cut the plexiglass sheet into 3 small ones for the projector mounting plate (extra for other projectors later)...and 1 large one for the ceiling mounting plate.
First plate mounted. I had to use M3 size machine screws to mount the small plate to the projector. There were 4 of these holes on my Optoma HD 72. Then, I had to use a 1/4in - 20 machine screw for the middle mount to add some security (seems like a tripod location or something sort of centered in between the 4 M3. Yep, Metric and SAE; awesome).
You could always just use the 1/4" hole in the center, but it flexed the projector casing too much and seemed risky to me. Then again, I could get a new projector quicker if it failed.
The holes for the Optoma HD72 are all seemingly on the left half of the projector. Weird for balance: I'm sure to find out.
I reversed the screws to go towards the ceiling to mount to the larger plate. Spaced out by more washers/rubber grommets, etc. All 1/4in here.
Larger plate mounted.
My biggest trouble was trying to figure out how I wanted to mount the larger plate to the ceiling and leave room to adjust x/y/z axis.
I settled on hooks even though they look pretty DIY I thought it would be easiest using these and the plates for when I get a new projector next year or whenever.
Now do I want to watch football or try to mount this thing?
EDIT: The main problem with my setup is accessing the filter. It is CONVENIENTLY placed so that cover can't be removed unless all of the mount is taken off from the projector. So, cleaned it once now....
I also think cooling should be okay since nothing is flush to the projector casing.