For these, I purchased a piece of white poster board so I wouldn’t have to deal with the wrinkles and variable translucence of the sheet I had been using as a background. I also bought a couple of work lights with 75-watt compact flourescent daylight bulbs. I only needed one, providing the light from the left. The other light is coming in through the bedroom window. It’s a sunshine day with lots of reflection off the snow.
Here there are in gray-scale: