I would suggest putting it in a plastic walmart storage box. You'll gave to cut a window out and glue in a piece of plexiglass for the light to shine through. Depending on the size of your light, you might have to cut the ends of 2 or more and glue them together.
Suspend the fixture in tomato cage and wrap with saran wrap???
I've never done it though, just suggestions.
THis is what I did...and it works great. I just cut the window in the 4" PVC and drilled a hole for the cord, hot glued it shut....used the plastic bag that our down comforter came in to use as window and hot glue it in place....2nd year running and ZERO issues!!
I use colored compact fluorescent bulbs on yard stakes for some of my lighting. I use clear jugs or 2 liter bottles with the top cut off as covers and poke a few holes in them above the bulb around the sides, but not on top with a soldering iron to let excess heat out. Mine ae hidden behind objects so the jug is not visible, just the light. Position the jugs carefully so the bulbs don't touch or get too close to the sides. Standard bulbs, or black light bulbs will be too hot to safely do this with.