YouTube member dalecampbellextras shows that a large mechanical kitchen timer can rotate more than just a small GoPro camera. Here he's showing use with a Canon DSLR and the timer still seems to rotate pretty well. I notice that in the video, there's talk about Center of Balance. If you've already picked up a Macro Rail Slider this could help center the weight. These mechanical timers are great for DIY panning rigs, but with a bit of string i'm guessing it can pull a camera across the Konova slider (no batteries required). [Thanks Dale]
Dale has some links to the products through his YouTube video, for eBay and Amazon the closest thing I could find similar would be the Large Kitchen Timers.
Large Mechanical Kitchen Timer
The traditional Egg Timer has always been used as a Panning Rig, but curious if anyone has taken that Rotisserie motor and used it for this same purpose?