Being a colour-holic, I collected some paint sample cards from a hardware shop recently, tho I had no intention of painting, but thought they may be good for something.I had a "Ladies craft day" at my place yesterday, so tangled one of them. Also taught two of the ladies how to tangle. They loved it of course and their second tiles were amazing.
Verdict? The surface wasn't too good to draw on, and eventually the pens ink wouldn't take, The ink sunk into the card and went pale; too easy to smudge as ink took a long time to dry on it; pencils used to shade worked really well; if I could match the colours for the white line space, it would give a pleasant gradient of colour; I think the idea is worth another shot, as ideas are coming for ways to improve the process! Perhaps you'd like to have a go?