Now it's time for this:
I used:A paper lunch bag
Fabric for the outside (and fabric paint, masking tape, sponge brush, etc. to paint the stripes on the muslin if you're doing that. There are tons of great tutorials out there for painting fabric. This tutorial is just for the bag part. You can jazz it up or tame it down anyway you want!)
Drawstring closure fabric (I used unpainted muslin. Cut 2 pieces as long as the top edge of your bag + 1/2” seam allowance and as tall as 1/2 of the finished bag width + 2” seam allowance so it can close in the middle.)
Interfacing (I used some cheap, light-weight stuff to give it a lunch bag personality.)
General sewing supplies like scissors, sewing machine, pins, etc.
Iron in folds (like a paper bag!)
Sew seam allowances down close to the edge, like hems.