I live around the corner from Swim Bike Run, makers of the SBR Rocker which is selling like hot cakes. I built my own in February for $200. I put on several coats of acrylic polyurethane so I can sweat all over it without issues.
I decided to go the route of using small inflatable balls and bushings down the middle. I also soldered together a pole for my unit’s controller.
I can post a link to the plans if anyone is interested.
