We are in Newcastle for a Workshop working on a new idea for tangible UIs that can be easily customized. The basic idea is to senparate functional parts of the system (electronics etc.) from the shell/tangible components of a devices. By this we hope to support innovation in a sustainable way. The skin of the appliance is printed (in 3D).
Nic Villar came up from Cambridge and he showed us some interesting materials... and obviously there is a shop (materials.
http://www.mutr.co.uk/) to get those... Look in the section for smart materials - there are probably many ideas hidden for now interface technologies - not only for tangible UIs.
We discussed how Polymorph could be used in tangible UIs - I think the challenge is to electronically control the material... obviously we played with the material to get ideas :-)