Another similar simple method to the one I currently use is to use a 1/8" x 1" piece of flat bar from HD and push drill a hole in it. You then make an angled cut from the top edge as shown. Then you offset the cutting edge (red arrow) slightly on the input side
PRO
It's fast and simple to make. Very portable. Just throw into your toolbox. Easy to make another if it gets damaged and make other sizes as well.
CON
It's a bit tricky and finicky offsetting the front hole cutting edge to get the perfect diameter desired. But once this is achieved it's very effective.