You could try a yoga mat bag or a mat strap
I go to conferences where I have to bring posters and those or what I use to bring the posters and they always let me take them on

http://athleta.gap.com/browse/produc...ccessories.jsp


http://athleta.gap.com/browse/produc...VTB0wG7m2kuTnQ

I am not sure if that is what you are looking for, but they are actually pretty helpful for at home use also