Martin Nash used to perform at the CNE with a mirror setup. It was a table with 2 poles that attached to the side. Between then, was a mirror that he could attach at a 45. The sides of the poles had hooks, onto which he would put his speakers. The whole setup fit in his car.

He had shown me photos of it and it was pretty cool. Hundreds of people all gathered around watching the table top in the mirror.

Cliff,
I am confused.
Your original post asked for suggestions for:
Quote "What I want is to be able to work in front of an audience on a table, and project what I am doing onto a screen" .End quote

The plans you posted above are for a transparency projector using bottom lighting.
You need transparencies if you are using lighting below the photo frame.
You were asking to project your work on a table.
Perhaps I'm not understanding what you are asking for.
Sorry if I keep on repeating myself but you won't be able to project your work on a table using the plans you posted.

Yep! That's the kind of set-up I described earlier that is common with cooking demonstrations.