Translum diffusion again. What you see on the (focussed) photo is a cheap dull plastic sheet protector in front of the matrix. At the top with no distance between the leds and the plastic, at the bottom with 1.5 cm distance to the leds. Just saying.
It’s not the plastic you use, it’s how you use it! 
Well, the surface of the plastic matters, too. With flat reflecting stuff it doesn´t work. It is the dull surface that does the trick.
@Stefan_Petrick I keep seeing you mention this translum stuff. Do you know where to get it in small quantities? I don’t think i need an 18ft roll…
They basic source for that are (still existing) photography shops. I would say go with open eyes through a stationery shop and look for adhesive foil made to blind windows. Check the acrylic polymers your hardware store provides. Experiment with materials you find at home. So to your basic question: sorry, I have no recommenations where exactly to buy small quantities for cheap.
Here in the US, an 18’ roll is under $40. Some entrepreneurial type could buy one roll (about 80 square feet) and then sell it for $2 per square foot and make a few bucks (eventually). Or sell it for $1 per square foot as a community service.
Or convince Adafruit to sell it as a useful accessory to their LED matrixies.
Let me know when you set up your shop, Mark, and I’ll be the first in line.
Spider-Man theather show in new york was done this way. The led Screens are only 8 m high and 2 m Side …
@Mark_Kriegsman I remember that I offered you guys a sample of that Translum stuff awhile back. It turns out that the stuff I dug into wasn’t the right stuff. I ended up taking material that my pop’s uses for his photography business, oops! So, I can attest that the Translum, will give you delicious diffusion at a very small distance from the LED’s.
Oh, and another note, hopefully @Stefan_Petrick will agree, the translum plastic is very fragile. If bent too much (which isn’t much), it leaves a milky white line at the crease and is horribly unsettling when gazed upon.
I agree absolutely. It is more a meditation than a job to handle that material properly. Gloves are also recommended as it picks up everything it gets in contact with…
For diffusers, I really like non-adhesive backed 4mil or 7mil thick stencil film, set about 10mm from the LEDs. It comes in rolls about 40" wide and about $3/foot. And you can find A4 or 8.5x11" sheets at art supply stores in a pinch.
I can’t find my roll, but I think here’s the stuff in sheets that I got a while back:
(and I got it from Blick’s in Old Pasadena in their upstairs drafting/architecture area)
What’s the appearance of this like when not lit? I get the impression translum is white opaque and smooth (can anyone confirm that?) . How is the grafix film?
@Ben_Delarre Here’s a small video showing off the stencil film sheet I got from Blick’s. Hard to video LEDs though, so it’s hard to get a sense of it. https://www.youtube.com/watch?v=rRaZd_OxKVU
Thanks @Tod_Kurt that answered my question nicely. I wanted something a little more opaque than that when the LEDs are off, so I think I’m going to try the translum, and if that fails fall back to 3mm white acrylic.
can be used to illuminate the diffuser LSD TV. Ask for possible service center in the of the broken panel.
http://olegart.ru/img/DCIM/au4831-backlit.jpg
http://laptop.nnov.ru/images/stories/lcd/image015.gif position 6
sorry for my English
