Since I got no response from WWG, so I think it should be OK to do it for personal use. I have converted some A4 Sheets to A3 and ordered yesterday.

Just now I received the package and the print quality and paper was great. When I compare those prints with my old (inkjet) prints then the color, the gloss is very improved and cost is almost same.

Now I have to look for a nice layout.

Sorry this slipped by. WWG is totally cool with having your sets professionally printed. In fact, you can modify the files however you like for your own personal use. The only thing that's not cool is redistributing them; file sharing.

As a substitute for foamcore, some people have used Medium Density Fiberboard, or MDF. Other people have used Matteboard like you would get from a print or photo mounting shop. Both of those have the issue of not being as think as Foamcore though so for terrainlinx you are kind of stuck. Usually people have been able to find foamcore eventually, it just takes some serious digging. Have you checked with art supply stores?

Sacretis