A stencil is a great idea! Brush a powder across it, then maybe a setting spray.

I was sort of thinking, well, you know how sometimes if you leave a can of spray paint sitting around too long it gets to that stage where it throws out bigger blobs instead of a fine mist? Make me a nozzle that does that deliberately, and then put some darker-than-usual spray tan in the can. :D There could be 3 or 4 colors, to mimic different freckle shades.

Your way is much better, though. Because rainbow! Or metallic purple, or glow in the dark, or anything! *heart eyes*