you can buy [sheets](http://www.precisionurethane.com/urethane-sheets.html) or [pads](http://www.precisionurethane.com/polyurethane-pads.html) depending on the thickness you want.
pick thickness dimension and hardness we strongly encourage you not to buy to hard material (>70A) because the material can be knocked or folded during the shipping and residual stress can be induce. unless you specify it to the company.
[Pads from Vishay company](http://www.vishaypg.com/micro-measurements/photo-stress-plus/category/coating/?subCategory=materials)