Hi, I usually have my kids color on a card (sometimes store bought, sometimes just construction paper folded in half). My H (separated, he moved out) generally has been really working hard to get me gifts "from the kids", but I do not put as much into his. I've ordered photo mugs with the kids pictures, framed a print, etc ---basically what I would do for my MIL post separation.
I did use paint and let them stamp their hands on a card once - it was cute. If you do a time intensive craft, do it because you'd think it was a fun thing to do with them...less for her, more for you/kids.
Faith is, at one and the same time, absolutely necessary and altogether impossible. --Stanislaw Lem