Dear Ilya,
Here I am a year later, and I still am trying different things for this problem. I now have a series of panels ordered which are all largish( 20x24, 12x18, etc. ) and am trying to work out a method. They want to be framed, but no glass.
I saw this website link from France- http://www.atelier-st-andre.net/en/pages/technique/fresco_technique/portable_fresco.html#Anchor-La-6934

Has anyone tried welding their own frames to plaster into? What does that involve? Is that conceivably a DIY thing, or would I need to call a machine shop?

I like wooden frames, but there needs to be something to attatch it to..

Any other ideas?

Also, they mention a lightened concrete. Has anyone tried this? It also says they don't make it in the US, but when I spoke with a contractor, he said he does use something which sounds like that on floors.
I only use portland cement in the first coat, but what about it???

Thanks so much!!