The current issue (May 2021) of Model Rail contains a short article on building a layout baseboard out of cardboard. While I can’t post the article, it does have a link to the Hazel Grove & District Model Railway Society, which experimented with this technique.
http://hgdmrs.org.uk/hazel-grove-district-model-railway-society/cardboard-baseboard/
While I get this is a proof of concept, I’m not sold on it. I like the idea of building a lightweight baseboard out of junk, but to me, it looks sloppy, especially at the exposed cardboard edges.
What do you think?