I was trying out an A3 led tracing panel for my C9.25 recently and noticed that the illumination from the panel wasn't completely even. Using A3 against the tracing panel still showed the illumination to be uneven, but better. I then tried placing an A3 sheet cut to a 9.25" circle just near the corrector plate to diffuse the light after it had travelled a little way from the tracing panel and it was heaps better. A3 paper seems a little flimsy in terms of its ability to withstand humidity etc, so I'm going to try a custom cut piece of flat acrylic light diffuser near to the objective of my C9.25 instead (probably with a small handle or something on it to make it easy to put on / remove). I have some on order from eBay and will cut it to size on my scroll saw if it ever arrives
I'm hoping that it'll diffuse the led panel light nice and evenly, and be long lasting. Fingers crossed! It's an ongoing experiment