On a recent shop hop I saw a ruler bag and decided I just had to have one. I found a pattern online - on the crafty site -
http://www.craftsy.com/pattern/quilt...ruler-bag/1401
It's from Pure Joy Designs and is the "Ready, Set, Go Mat and Ruler Bag".
My 18 X 24" cutting mat slips right in. A 6 X 24" ruler fits in an outside pocket - held neatly between the straps. The clever thing is the pocket is not 24" long. It has two outside pockets and the ruler slips into the first one and down through an opening in the bottom of that pocket into the lower pocket. You make the inside pockets to suit yourself. I have 10 interior pockets and 4 more on the outside that don't include the 6X24" ruler pocket. I can't wait until the retreat I'm going to next month! It is quite heavy - 2.5 pounds - so I hope I can carry the thing when it's filled!
I poked paper in some of the outside pockets just so you could see them. I took pictures of the interior pockets after I'd sewn them to the lining, but before I put the bag together. Notice that one pocket could hold a magazine - or downloaded pattern - and one holds another ruler. This is a BIG bag!
For the outside pockets I used scraps of things I've made and pieced it to the size required. The rest of it - including the interior pockets are ugly fabric I had on hand. You could make it really cute with sewing-themed fabric, but I really like my "ugly" one.