The outfeed roller shown in the photo is simple and inexpensive to build. And, as you can see in the drawing, all it takes is some scrap lumber, a short length of PVC pipe, a dowel, and a few screws.
The roller is designed to be clamped firmly to a solid support, like the sawhorse shown in the photo. This way, once it's set up, the outfeed roller stays in securely place, and you won't need to worry about it falling over or shifting out of position.
Have a nice weekend,