Neat walkthru on DIY projection

http://www.tomshardware.com/howto/20041113/index.html

In principle, both store-bought and do-it-yourself projectors consist of a liquid crystal display backlit by a light source. An old or used flatscreen LCD is ideal for the display; these can be picked up for prices starting at around $100. An older 14" or 15" office-type TFT monitor that is due for replacement by a 17" or 19" model is well-suited to the task. There are also flatscreen monitors that have diminished backlighting or even none at all. These devices are ideal for use in constructing your projector. If you don't have a suitable used display, a $200 bargain from your local electronics discounter will do the trick.

Once you've settled on a screen, you can turn your attention to getting hold of an overhead projector. Used devices can be had for as little as $50. All in all, a homemade projector will set you back little more than $250, working on the assumption of XGA resolution, as we said before.

 

Nice Stuff - interesting concept with some pretty good guidance. Am going to try my old traveling overhead projector (not a pass through light source, but reflective head) in conjunction with a couple of different LCD's to see what I can throw on the wall and whether or not it sticks. Will advise when I get back to the home twenty. Never even thought about this until your post - thanks.