Fold over on wrong side and sew pocket for elastic (about 1 inch), feed elastic into the pockets at both ends.
flip right side out.
Cut a strip abou 8 inches long by 1 inch wide for handle. This can be attached after bag is sewen together or while length wide seem is being sewn.
I have these in our bathrooms as we use plastic grocery bags as garbage bags. I also have one next to the washing machine and in the kitchen. I saw an organizing post recently where these bags were assigned to each member of the family and held all their socks. I'm guessing this would also work for kids underware.
All photos taken by JS Foto who is available nation wide for photo shoots!