Hi! Necessity is the mother of invention! Do you mean conductive paint on a bare board, or another type of paint to cover the copper, like those pictures you do as a kid covering the colours with black poster paint and scraping bits off to make the image (the fondly remembered fireworks and bonfire night pictures primary school art class classic!)?
Oh hell, I do remember that art board.
Any paint that acts as an etch resist. I've used Fablon and nail varnish in the past, and wouldn't recommend either.
There are conductive paints but they are expensive and are probably useful if you want to repair tracks (?e.g. car window demisters?), or have an "arty" type thing such as a flexible board/fabric, or something quick'n'dirty, or for instant gratification with young children.
I'd wondered just how bad and time-consuming it is to somehow remove the unwanted copper by hand without etching, but think it's obviously not to be done except as an experiment out of curiosity when time is not an object.
If you can use a hacksaw, or have a sufficiently steady hand to use a dremel as router, then it can be done. I've used the latter for tiny RF attenuators: 2 SMD components, 2 connectors, 1cm*1cm.
I'm planning on using conductive copper tape for RF experiments, since can be quickly cut to shape and trimmed.
There are helpful links on your blog/web, and the articles are interesting, thanks. I didn't know that ceramic SMD caps need warming first - important to know before the event!
It is easy to get too hung up on possible problems that are principally relevant to high-throughput situations. Having said that, plastic packages (e.g. SMD LEDs) can be a problem since they are very hygroscopic - they visible *****.
Unrelated but related: Chip Art is fun to see; and this web has a lot of old circuits, quite beautiful to see, I really enjoyed the walk through history, it's in Italian but you don't need to understand it and some is easy to figure out from the words anyway:
http://ummr.altervista.org/before_microprocessors.htm
Thanks for reminding me of that. I have some
very pretty pictures of thick-film hybrids from a 1970s advertising calendar. I must scan them sometime.