I like footers idea pink foam painted black. If you have access to the outside of the window, you could use the Cinema trick of packing blankets hung against the window to block out light. Packing blankets are great for sucking up ecess lumens, Not as good as new and improved Lumi-Suck from Rosco but still pretty good.
Hey along those lines. Latex paint does not like to adhere to foam;, pink blue, etha or styro. Here's a little trick that helps a lot. < 'course I'm giving away a trade secret for free. >
1 gallon latex paint
2 tubes Latex painters chaulk. < not silicon>
1 cup Joint compound
1/2 cup water putty
1 five gallon bucket
color and mix paint into 5 gallon bucket
squirt both tubes of chaulk into paint drop in joint compound a little at a time as you continue to stir with drill motor attachment
pour in water putty
bake at 350 degrees for 15 minutes and Viola a souffle for the entire shop !
no don't bake it. paint it on almost anything. Add more chaulk if you notice it not adhereing very well. I've had great success with this scenic dope. by adding more joint compound you can make a wonderful texturing material that won't crumble when walked on. < the latex chaulk binds real well with the gypsum joint compound to make an extremely tough yet slightly fexible surface>
I know it's not right on with this thread but Audioslavematt sort of inspired me with his comment.