This is a video slider I made my self. It is adapted from the zazaslider web plans. On their plans they use a 16-60 rail, and I wanted to build a system for larger camera rigs so my rig is built with the 20-80 rail system. It is not a portable as the 16-60 system, but it is solid. I also went with a 150mm carriage in place of their 100mm one.

Zaza parts:
(1) WS-16-60 Drylin 'W' rail 1000mm
(1) WW-16-60-10 Drylin 'W' carriage

My Parts:
(1) WS-20-80 Drylin 'W' rail 1500mm
(1) WW-20-80-15 Drylin 'W' carriage

If you are using small to medium sized camera rigs the Zaza setup is %100 proven, and will save you a bit of money and time.

If you run a heavy rig and want a longer rail run then go with the 20-80... its impressive.