Benny, it was not my meaning to "cast down" your idea, I'm just sharing my (quite substantial) experience with lasers in display applications.
You will need a lot more laser power when you scan a connect-the-dots picture than when just holding the dot stationary. A normal laser pointer is clearly visible indoors in the middle of the day, but even scanning a simple circle on the wall it is difficult to see under the same conditions.
When I talk about accuracy here I'm not talking 1/10 of a millimeter. It would be difficult to build scanners that can hold even say +/-5 mm (+/-0.25 inch) at 0.5 meter from the scanner or so. I'm just saying it's a difficult project if you build it yourself, or expensive if you buy it.
Feel free to use my knowledge in this area, I'd be glad to help! It
is a cool project
.
Arvid