This idea originated at a conference years ago where an expert art teacher told me how she would use marker tops to create small scale murals. I didn't have a lot of marker tops at the time, but I did have tons of nubby crayons. Hence, I would give it a try!
I assigned this project to a small group of fourth grade girls, however I think with proper guidance much younger ages could also accomplish this. We used the following materials: one side of a cardboard box, crayons, and glue-all. I would not recommend school glue because it doesn't have the permanent quality needed.
We drew out a pencil sketch of Van Gogh's Starry Night on the cardboard, then we poured glue in lines across one section at a time, placed the corresponding color crayons on the glue, then continue forth across the entire image. I think the results are rather impressive considering all the materials used to create this work were discards.
Our interpretation of Van Gogh's Starry Night
A couple of pointers about making something like this: I recommend shaving one side of the crayon to create a flat edge that will rest parallel to the cardboard base. I've found that many will pop off easily if they remain cylindrical. This project takes a while and a lot of crayons. If you are working small then I would expect you could finish quicker, but this particular piece is over a foot and a half wide. Lastly, use a lot of glue. Pour it on seams, fill in little gaps.
So far I have a crayon mosiac started at my primary school (K - 2) of our mascot, a giraffe. I would also like to create one at my intermediate school although I'm not quite sure what we should create yet. If anyone has any suggestions feel free to share them!