Just paste it form my other post:
Paper
PRO:
-cheaper
-easier to cut
-give a sharp edges and more exact dimension
CON:
-time consuming
-a lot of detailed cut
-more parts
-to make a dent or build thickness requires more effort
-without resin or fiberglass, it is just not strong enough.
Foam
PRO:
-less parts
-it can be bend, more organic shape
-sturdier
-it can be finished without fiberglass/resin
-faster build
CON:
-some find angle cut is troublesome
-less detail
There are more pros and cons, and the above statement still can be debatable. And cons can be converted to pros with experience/knowledge/creativity (and so on), and it also can go all the way around.
To use paper or foam is just a personal judgment. These are just a media to be use to create replica. Just like clay and so many other options. Other member tried to do hybrid (combining paper and foam) which I wanted to try myself.
To help you determine, perhaps you should look at:
-budget
-skill
-tools available
-patience level
-available time vs deadline
-availability of the supply
-creativity level
-expectation vs reality check
-source of information/help/assistance
-others
Hope it helps
