Vapour deposition of metals is a standard industrial process, Tony probably has an 'oven' in his workshop... and if you add metal to glass you get colours. Plus there's some neat things you can do by layering the metals, so you get diffraction effects.

Steve could probably spend a happy afternoon or two learning how, either from Tony or JARVIS. Hmm... I wonder how JARVIS would feel about creating art? Although the stuff he does with Tony is as much art as engineering.