Original suggestion is "nail polish + recycled lightbulbs for garden art." I think they'd make cute Christmas ornaments, and there has to be better paint and glazes than nail polish, with its tiny brushes.
how to rejuvenate solar lights. We learned that ‘frosted’ plastic reflects light away from the solar cells; clean, clear solar cells can capture much more light. Clear nail polish is perfect for rejuvenating plastic-covered solar cells!