Soeren you may have already thought of this and ruled it out but if you are useing it for an encoder and its not too large you might be able to just print it to transparancy if nothing else it's worth a try
That is what I've been doing for years for stuff needing less accuracy, but it doesn't really gets all that perfect (try studying a print in a microscope - it looks like splatter paint). I mount it on a thin polycarbonate carrier to give it structural strength though.
I've seen other people use transparency to make encoders and its cheaper and quicker than the alternatives course thats as long as you have access to a laser printer with enough resolution for what you need
The coded disk in the photo above, I've made by printing to a piece of drafting "paper" (the matte film stuff) and used that to etch it onto a piece of PCB material (same method I use for making PCBs). The drafting paper takes the toner somewhat better than regular transparencies, but still have tolerances, just like the etching process itself has.
I use comms fibers mounted in a machined block of rigid plastic (don't know the type, just something I had handy) for reading it (from the foil side, with IR LEDs on the other side) to get the size down (this particular disk is around 4" in diameter
) and the precision up, if anyone should be curious.
I can get an A4 size sheet run out on film from a repro firm, directly from my CAD files, with a hysterical perfection and it will cost me no more than around $10 ($20 tops), depending on how fast I need it (and several coded disks could be made in a single sheet).
use this film directly, or etch it onto copper clad board, but I'd like the strength of steel to make it last - besides, I really like Stainless Steel
I have yet to get a price on the foil etching though.
Thanks for your thoughts!