I set out to make my own by purchasing bikini or low rise underwear and also briefs. My intent was to cut the bikini/low-rise ones on the sides and crotch and sew the panel onto the insides of another pair of briefs. This looked like it would create the same panel/pouch that is inside the expensive ones.
I tried them on first to see how it might work with the bikini/low-rise pair going on first and then a pair of briefs over top and they fit perfectly. The top of the bikini/low-rise pair stops perfectly at the bottom of my flange. After my "fitting", I did not feel the need to cut and sew anything.
So, now I wear 2 pair of underwear all the time. They are made of light t-shirt material and they work like a charm. They are not cumbersome and my pouch does not lie on my skin because it sandwiches perfectly in between both pair and stays put very nicely. I do angle my pouch towards the middle and that keeps it from going down and out the bottom of the leg.