Has anyone tried painting on IMBC like it's done on fondant? I imagine if you chill it till firm it would have a sturdy surface, but I don't know if you would use the gel/paste color in vodka, or the gel/paste straight or I read somewhere that someone suggests oil-based candy color for IMBC. Any advice?
Also, does anyone know how difficult it would be to make an impression mat? I'll could probably paint freehand if I did it, but getting the exact same flower all around the cake would be a challenge. I've seen some on the market that are nice, but it sure would be nice to design my own.

I've never tried it, but like as you said if you refrigerate until firm you would have a hard enough surface to work on, but my concern would be the colors beading up/not taking to the IMBC... oil based/candy colors might work... can't hurt to experiment. Spread some IMBC on a cake circle and chill and see what happens when you try to paint it. Better than experimenting on an actual cake! lol

Impression mats will not work (well) on IMBC or SMBC. Neither will painting or airbrushing, sorry. You might be able to do it with oil based colors, but realize that thoes will never dry. Any other medium will bead up.

I "painted" on a cake frosted in IMBC with another color of IMBC in my cake design class. It looked like a Limoges box. The flowers I painted on looked Impressionistic. The cake had come out of being in the freezer for a while to do that. I'd be curious to know whether gel paste color dissolved in vodka would work. Let us know!

You all were right. I bought the candy color hoping I could paint it on and it would adhere to the buttercream but it's been refrigerated for seven days and it's still wet. Oh well, at least now I know.

I have used an air brush on my smbc. No it does not dry but you can paint it.
If you touch it you're toast but other than that...