Could you have painted it on tin? like sand it rough so oil would stick? Would the oil stay wet if you wrap the box in plastic wrap? Cardboard would make sense so the painter would know where to paint. maybe a canvas of some sort. People might buy such a paint kit like this.
Discussion
Most surfaces can be painted on if you put on a couple coats of gesso first.
Oil paint takes several days to dry to the touch and months to dry completely.
I use an archival quality cardboard that is primed with gesso and mounted inside the tin.
The small tin containers serve as pallette, display, and safe storage all-in-one!