What is the best material for surfboard blanks

[superlefax]

Hi guys,

I want the feed the CNC for making a nice surfboard shape. What core material would you recommend?
I’ve heard that XPS is quite a good option:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=2ahUKEwiCucH40LDlAhXDfFAKHQ50A48QFjACegQIAhAB&url=https%3A%2F%2Fwww.obi.de%2Fgeschaeumte-daemmstoffe%2Fxps-daemmplatte-jackodur-kf300-standard-gl-40-mm%2Fp%2F6563654&usg=AOvVaw1VYyliig6NbWT_5_rjPzud

Any better options?

[V_S]

Austrotherm or Jackodur are very similar.

[tylerclark]

5 lb or 8 lb foam works great. I’ve made a few boards. 2 lb foam works OK too, but it’ll dent easy.