I made one a few years ago from a free pattern found online. Sadly, for the life of me I cannot remember the site. And if I could make it in the door of my sewing room at this point, I'd try to find the pattern I printed. It was a general sewing site if that helps any.
Velcro closure for the top edge; ribbon to thread through the clip. It also had a front zippered pocket to hold credit cards and the like. It's awesome and all I use for a wallet now. Most times my phone does fit in the back pocket of my jeans and I just have cash in pockets as well. Those few times I need the credit cards I clip the pouch to my belt loop. Have license in there as well so most times it just lives in the car.