If you happen to have an IGUS W1080-B Linear Slider and are looking for a way to get consistent movement, Servo City now offers a DIY Motorized Kit. You may have seen me working with a prototype version of this slider in a past video when I designed a simple infinite loop auto reverse switch (seen here).
With a slower motor in place you can use this to achieve long time-lapse sequences, or with a faster motor in place you can use this for real time video (noise will be apparent from the motor).
The kit comes in dozens of little pieces, but with patience was easy to assemble following the video instructions:
Actobotics - IGUS W1080-B Slider Kit Assembly (part 1)
Actobotics - IGUS W1080-B Slider Kit Assembly (part 2)
Servo City IGUS W1080-B Motorized Slider Kit