It was suggested to me in a feedback session on my work in progress that I look at making the puppets head out of something like balsa wood or paper mache which will give it a more tactile and angular feel (and will also be extremely lightwight!). I am going to try those particular methods but this got me thinking about other lightweight materials that may work well.
 I have never used mod roc before but have seen it used in a previous production that I worked on so thought I'd give it a go. Seeming as I had made a sculpt I thought I would apply the mod roc straight onto this (cling film wrapped around the sculpt to protect it), let it set and then cut it open to take the sculpt out then reseal.
Although not great at intricate detail this was an extremely quick process (if you already have a sculpt made) and is extremely lightweight. I am going to build on top of this to make it look like a character so this might solve the problem of lack of detail to begin with so there will be a post again soon of how that goes...