haven't tried this myself, but I did read about using photocopier toner as a resist with ferric acid as the etchant. you make a print/photocopy in black and white of what you want (with 'white' being the bit to be etched) and use an clothes iron to iron the pattern onto the clean steel. Then etch.

I don't think stainless requires any more aggressive an etchant, but, I haven't tried, so testing should be in order.

that was my plan. i can do very accurate toner printing at the office, and in theory can force extra dark prints.

Toner transfer is a common method for etching printed circuit boards.
Does ferric chloride etch steel? I know it etches aluminum like crazy.
I remember from high school electronics class (a couple decades ago)
that the etchant we used for PC boards would dissolve steel wool quite happily,
but I can't remember what the chemical was. It came as a whitish powder
that was mixed with water and the resulting solution was clear.

Are you planning to etch all the way through, or just on the surface?

Not sure about the ferric chloride, but I know that the OTHER PCB etchant, sodium persulfate, etches most metals. When I was in college, a stopper with a steel ring through the middle was used to seal a vat of the stuff and it very quickly etched enough of the metal away to start leaking.

I've done a fair amount of etching of PCBs with sodium persulfate, both using toner transfer and using UV light exposure setups. There are a few things to keep in mind-

1. Toner transfer kinda sucks. It's hard to get fine detail- some places are going to get over etched, some under etched, and nothing is going to come out exactly like you thought. If you're thinking you're going to etch a finely detailed image on a sheet of steel, forget it- it involves too much area being transfered to.
1a. If you don't believe me, go ahead and try. I'd recommend buying the specially designed sheets that are out there on PCB making websites- not cheap, but worth it.
2. Heat and agitation make a big difference. If you can find a pump that will recirculate the etchant without any intervening metal components, that's best. Second best is an air pump and one of those aquarium air stones that is intended to form a curtain of bubbles. A small aquarium heater works just fine for the heat source- you want it warm like bath water, not McDonald's coffee.
3. I'm not *certain* it will work on stainless, but I'm betting it will.
4. If you use the ferric chloride, don't get that stuff on anything you don't want stained or etched. The sodium persulfate is more forgiving. Comparing the two page entries on Wikipedia, I think I'll be sticking to the sodium persulfate in the future, thanks.

So, all that said, have fun, and report back. I'm particularly curious about whether the ferric chloride will work on steel.

i'm looking at more like a ruler than a really detailed graphic, so as long as i can get decent lines to pop it's all good.

i can also dope extra toner on a print if need be to make a heavier resist.

Another thing to consider...

Is this going to be a one-off? If so, you can probably put up with the fiddly details of
toner transfer. If you're gonna make a bunch, you might be better served by a photoresist
process.

one maybe two off.

found my trusty old copy of The Complete Metalsmith last night, which has basics on EVERYTHING relating to metalwork. the have a bit on different etching techniques. it sounds as if the new professional edition has a lot more info, though. if i get the new one, i might have to donate my old one to the shop, once we get a home.