First take an old binder and cut off the covers. Or you can use something else flat and hard that you can staple through or maybe super glue. also a binder with a pocket will help so you can use a pocket to hold paper.

Lay both your binder covers on your fabric. let the bottems of the folder be about an inch and 1/2 away from eachother. Then cut one big rectangle around both covers leaving 1/2 inch of extra fabric around the 3 sides of each binder.

Staple the extra 1/2 on to the covers. or maybe glue it I havennt tried it but it might work better.

Cut out an extrea small rectangle of fabric and staple that onto one of the covers. Be sure to leave a side open. this ouch will be used to hold colored penciles or whatever other art suplys you want to put in there. staple it a bit lose so things can fit in there. (i created another small puch to hold just regular pencles you can make as many pouches as you want)

Cut out strips of fabric and staple them to the cover to make handles.

Now your done. use the pocket in the folder to hold paper and the other fabric pocket to hold art supplies. :)