Nijatech sells Cheetah which is TPU with a shore hardness of 95. This is some tough stuff. I have made faucet washers out of it and it is working better than the soft ones you buy in the hardware store. I have also make a USB microscope cover ring to use when inspecting knife blades during sharpening, so far no cuts.. The cheetah is also easy to print, sticks to anything like cement but is on the pricey side. Also not really good if you need support for the model. Being a US based product not sure of availability in England. As far as elasticity goes, much less than Ninjaflex.. Details on their products can be found here https://ninjatek.com/

Mushroombrew, I am located in the Philadelphia PA area if you happen to be near by please let me know as I have contacts at the Enabling the future Chapter at the Drexel University bio engineering lab who I am sure would be interested in assisting. If not near by, I wish you lots of luck on your collaboration and project and please let me know if I can help in any way.

Doug