I happened upon this projector during a recent search. The light path is a little unusual. Maybe someone could just use the mirror projection pathway or one simular to help in their folding of the light pathway.


http://www.nec-pj.com/products/wt/index.html

It also doesn’t use a glass lens. Instead it uses the mirrors to focus.

DJ

The only problem is for a diy'er I don't know where you would get the special mirrors
It's funny we always are looking at making 'long throw' PJ and they are advertising the merits of the 'short throw'

I was thinking about this projector myself. I am looking at making a short throw projector, so I started thinking about how to replicate this cheaply.

I am not an optics person, so I am not sure if this would work, but this was my idea to test.

I came across these:
Flexible Mirrors

I was thinking of cutting thin sheets of particle board and sandwiching them together to form the shape, then use these mirrors stretched over top of it.

I was concerned about the quality of the mirrors, but you can purchase small pieces cheap for testing.

I decided to go a more conventional route and bought a 10mm focal length projection lens off ebay cheap.