There's a bit of a learning curve in heat forming foam. Not enough heat and
it breaks. Too much and it's not exactly foam. Also, there's a capital
investment in whatever heating apparatus you choose.
For a small project, consider strip planking with foam.

dg wrote:

Looking for ideas on what foam coring product I could use to make a
dodger hardtop.

A guy in the marina recently cold molded one out of door skins wood
and epoxy. Seems to me that making a male mold and heat draping some
foam or something would be a better approach than driving and removing
3000 staples.

Maybe balsa would drape more easily?