This is an idea that I've been (pardon the pun) sitting on for quite some time. 

To make toilet paper, take the cheapest, thinnest napkin you can find (or tissue) and cut it into strips that are wider than you want your roll to be, and wrap them around a thin straw.  Then trim the ends with a pair of sharp scissors.  I made this with the napkin and straw inside the cutlery packet for school lunches!

Happy arting!