Opal glass would provide excellent diffusion (producing a Lambertian distribution of the light source), but might be difficult to work with in your lamps. You might try a fabric shop for translucent synthetic fabrics, a photo shop for diffusion film, or Amazon (see http://www.amazon.com/Rosco-Roscolux-Diffusion-Diffusing-Material/dp/B000B73OQY) for some material used in theater lighting.
Blog That A-Ha Moment Larry Desjardin 3 comments Have you ever had an a-ha moment? Sure, you have. The Merriam-Webster dictionary defines it as "a moment of sudden realization, inspiration, insight, recognition, or ...