Following the directions from my images, it should be pretty straight forward to make your own motorized dolly.
But remember this requires a few more tricks than just 3D printing:
Buying parts online, most of them on ebay
Getting small fasteners
Machining pulleys to fit bearings
Soldering cables to motor
Luckily, everything is explained!
Step 1: BOM
Here is everything you will need to get to succeed.
STL Files available here as well as a pdf file with hyperlinks.
Step 2: Clamp
You will need to build 2 clamps.
Step 3: Carriage
Build your carriage.
Step 4: Motor
Assemble the motor and its gears.
Step 5: Further Details
Here are more details to help you to succeed.
* Belt length is 1990mm *
Step 6: Get Out There!
Go try it!
I used :
Magic Lantern on my EOS 7D for setting time-lapse
LR Timelapse & Lightroom for editing
After-Effect to render the video (sometimes I used a warp stabilization at 1 or 2% because of the wind..)