If you love building and tinkering, here's a look at another fun little project idea from ServoCity.com. They've added a new low friction channel slider that has very low tolerance, can accept a decent load, and that slides over their lightweight aluminum channels. In this video they have assembled a drive system that pulls the carrier through the channel, to work as a video slider.
These aluminum channels can be purchased in various lengths if you're looking for longer or shorter runs, and the motors can be swapped out for faster or slower RPMs depending on your project. The overall design allows these motors to pull quite a bit of weight even vertically, but if you're looking to carry heavier camera systems, just make sure to look into the channel slider that wraps around all four sides (here).
Now if you're looking to do some tinkering of your own, I highly suggest taking a look at the dozens of videos showing you step-by-step on how to build these projects at the Servo City YouTube Channel.
For more information about the Slider Kit A, take a look at their Channel Slider Kit product pages which shows examples and a list of parts required to assemble.