Well to be honest, I've got some "plans" in the works that I hope to reveal in full soon. This might sound a little cryptic, but I'll explain in (hopefully) a few days. In short though, I'll be able to spend a lot more time focusing on photography in the near future, and working on both a panchromatic emulsion and a screen are gonna be high on my personal to-do list.
For a screen, I'm more or less set on an idea that would create something resembling a Dufaycolor reseau, utilizing the original technique described by Louis Ducos du Hauron. Basically it would be a dichromate (or similar) procedure with mutliple etching steps.
If I thought that coating a screen with starch grains and subsequently filling in the interspaces with carbon black could be easily done, or rather, if I understood how the heck that was done!, I might be interested in thinking along those lines. Dying the starches and varnishing them onto a plate would be trivial, but the coating/calendaring procedure is beyond me. There are a number of other ways that one could theoretically make a random screen reseau, but none that have really struck me as practicable. I'd love to know if anyone else has some ideas on that.
In other news, I know that Denise over at the Light Farm has started messing around with panchromaticity seriously and she too is interested in reproducing the Autochrome. However, she seems to be taking something of a hiatus (or she's holed up in the lab!).
Regarding the dyes that one could use in coloring starch grains or similar, we needn't look further than the acid dyes utilized in Kodak's dye-transfer system. Just as is done with some Wratten filters, combinations of C+M, C+Y and M+Y can get us the appropriate red, green and blue filter colors, and they'd have rather good permanency. Jim Browning has published his set of dyes, and there is a large list in my dye-imbibition thread. All of these are relatively easily obtainable "articles of commerce".
On the other end of things, lately I've been identifying a vast number of spectral sensitizing dyes (here, see the latest handful of posts) that could be used in emulsions; particularly old and cheap ones.