Elmer's Glue on Canvas, then paint the whole thing. I have totally done this, but with a hot glue gun. Elmer's Glue seems to be a better idea since hot glue leaves behind strings and is harder to work with.
this chick made this from markers and glue sticks---"The artwork is done with hot glue and a marker! It was very inexpensive, as I used left over house paint, a half price canvas, hot glue for a 3 D effect, and a Marks A Lot marker.