How to make an armband

Get you a sock, we are using a child's sock because its for a child's arm

Lay device on sock

Cut two inches longer than device

Turn inside out

Place on arm like so with sock cuff at top

Place device on arm

And pull sock over the top, so that it's now right-side-out and cuff is on the bottom

Now you have a washable custom armband that fits perfectly!