I built one out of an old sewing machine and I used a rotisree BBQ motor for my drying rack. I built it more than 10 years ago and it's still going strong. I've wrapped more rods than I can remember with it.
I borrowed a power wrap from a friend and I've been using that for past year. I've become use to being able to make all the little adjustments so when I give the power wrap back I'm going to redesign my rack.
I'm going to use elevated copper pipes one on top and another about 1 inch below with two on each side. They will serve as tracks for the small wheels that I will be placing in middle between the two. Your probably confused as hell right now but if you could imagine it would like the frame of a roller coaster with the little wheels riding along the track.
You can buy the small wheels at Home Depot in the wardrobe/ sliding window/ shower door section. Make it so that you can adjust to contour the blank. If you know what the power wrap looks like you'll know what I mean or you can go the easy route and just cut a v in to a piece of wood add some felt and your done. That's how I made the first one. All you need is a little time and some imaginition. Hey that's what wrapping rods is all about.