Here is my build of a video camera slider based on cnc pieces and some aluminum shapes I made with a water jet machine cutter.
Linear bearings you can get from here
CNC shaft supports from here
I used anodized aluminum tubes of 16 mm diameter that fit perfectly the bearings. I also tried raw aluminum pipes bought at the local depot but for some reason they are just half millimeter too large and doesn't allow bearings to slide. I'll try to sand those pipe thinner as the anodized ones make a noise when slider runs.