Anything can be a canvas. Please keep that in mind next time you have construction, or deconstruction, scrap materials that you can't find a use for.
For example, when moving from one apartment to another, you might find yourself in possession of a spare door (these things happen in the world of Cambridge Freestylers). We kept it with the original intention of using it as a door in the new apartment, but the design plans changed and it wasn't the right size for the new doorway. No worries, it was the right size for a door-sized mural.
This lovely piece or birds at a body of water brightens up a bedroom in the new place.
Of course it is totally portable and still usable as a door, but right now just rests against the wall in grand fashion.
Happy freestyling, and painting.