Well I have a desk that I thought to expand by laying a 1M x 1.3M MDF on.
If I need the whole area to be soft I guess I can lay something else on top of this MDF sheet, like cork or bathroom rubber carpet?

...Looks like I'm going to the hardware store, Horrray!

Edit: Medium Density FibreBoard http://www.design-technology.org/mdf.htm