Sharpies are awesome. Our kid needed a footstool to reach the bathroom sink, but I can’t stand those boring plastic ones.  Instead, I got a simple, plain wooden stepstool from The craft store, doodled on it with sharpies, and BAM–magical awesome stepstool. Ya know, like ya do.  I think I sprayed a layer of acrylic varnish over it to seal it, but mainly only for kid-messes.