The tutorial is now unfortunately only to be find in webarchive (without photos), but I found the idea so good that I wanted to present it here anyhow.
I think that it should work as well with taping thin paper on the glass instead of frosting it.
Nice, isn’t it?
Links:
The original site doesn’t exist any more and is now available through webarchive: Anleitung Votiv -Glas im Glas (German)