My husband made a felt pouch as a WEB and he still uses it to this very day to carry novels and books in the field. Get a piece of heavy felt, not craft felt, and cut to 10-12 inches by 30ish. Fold into thirds, like a letter going into an envelope. As you are looking at the folded felt, sew the middle flap to the bottom piece with a straight stitch on the two open sides. (Have the boys draw on a line with chalk and a ruler.) Trim the top flap to a point, or a wave, or whatever. I'll try to post a photo later today of my huaband's.
If you have a crafty mom or two, see if they'd be willing to teach the boys how to use a sewing machine. Valuable life skill.