There is a well-known mosaicist I found a couple yrs. ago on the net (can't remember his name, but he had mosaiced a Longhorn) that mosaics on paper mache. I think I remember he said "not directly", though. I think he uses rigid wrap. If I were to try your project, I'd wrap it w/rigid wrap - found a HobLob - and give it a couple coats of gesso b/f mosaicing. This, IMO, w/give it a nice sturdy, smooth surface. And, yes, Weldbond w/be a good adhesive. However, in my experience, Weldbond isn't good for someone w/no patience, cuz it slips/slides too much UNLESS you pour some out in a little plate, and let it get tacky. I also use Aleen's quick dry glue. Of course, this project is for interior use only.