What material is used for the flexible MEG headcasts?

For some projects at the DCCN we use flexible MEG headcasts to reduce subject motion and to allow precise repositioning over sessions. The procedure we use is derived from the publication by Sofie S Meyer, Gareth Barnes et al. (2017) Flexible head-casts for high spatial precision MEG and is outlined in some detail on https://github.com/Donders-Institute/meg_headcast.

The foam we are using is https://www.smooth-on.com/products/flexfoam-15/.