Somebody (can't remember who & search doesn't find it) here posted about "Biggest Little Christmas Showdown" a US competition show where miniaturists create miniature houses with a different Christmas theme every week, & I've been watching. This week was retro week & one of the competitors was making....something, & they were using Illustration board instead of foam core. Turns out that illustration board is better when painting with acrylics because it won't warp from water like foam core. I have never heard of illustration board before, but since I have had much trouble with warping foam core, I am most definitely going to try illustration board the next time I need to make a wall, hopefully it cuts easier too.