konakoa, We have communicated a few times. Thanks for posting your research and results. Saves many of us fruitless experimentation. I plan to soon make a 10x10 version using Chinese 12"x12" 1000 Led video lights I already own. I think one will be plenty, but 2 could be mounted in a mixing box. I first bought the 3400K to 5600K variable 7"x10" LED model. I was thinking I could vary frequency but that may not be necessary, as your research seems to show, Initially I will just use one white spectrum. The 12x12' are all 5600K. I am wondering if the higher frequency 5600K LED's will adapt to the MG filters as easily as lower frequency light. I believe most old enlarger bulbs were 3200K.
The US. Plastics source is great, I had already scoped them out. First I will try diffusers that came with my lights. I use McMaster Carr and Grainger for other raw materials.
One thing you did not disclose is printing times. Do you have any plans to discuss them?