I made one last year out of pvc pipe. Cut it to the length of the longest plug, made 6, duct taped them together, and then built a bag to fit around. Despite the fact that it's no longer pretty (trim is coming off, side mesh pockets ripped to shreds), it still functions very well. I'd suggest the canvas fabric, plastic clips (not velcro), and grommets in the bottom for drainage as main points. And the thing only costs about $20 to make.
