Ikea sells anti-slip felt mats made of a material that look just like that. They come in pretty big sizes. The one I have is 5.5'x7.9'....
But it has a very light coat of latex, for the anti-skid / anti-slip feature. Might make working with this a bit more challenging. I have been planning on texturing it with acrylic caulking and making a 'Tobi's mat'.