Materials
2 pieces 3.5" x 6" (or whatever size you choose)
1" velcro (sew-on and not adhesive unless you want your needle to get all sticky)
Attach Velcro
Separate the velcro and attach one centered about 1" from the top to one piece and 1" from the bottom on the other piece.
Place your pieces right sides together, making sure the velcro is at the top of one piece and at the bottom of the other.
Sew together the two pieces using a 1/8" seam, leaving a gap on one side for turning.
Turn right side out and poke out the corners so they're nice and neat.
Press and fold in the open gap.