This page gives you the dimensions so you can draw this clamp which holds the two ends of the toothed belt together. You need to make provision for a clamp to screw on to your lifting platform (or bolt on).
The two ends of the timing belt get clamped in place by the blue clamp shown below the timing belt. Here is a link for drawing it:
Here is a link to the Jaycar page where this switch is. Explore the Downloads tab and you will find a set of drawings that give all its key dimensions
This page has movies that illustrate design options and ways of organising the components nicely into the available space. Also a video on designing a lifting plaftorm, and videos on drawing left and right grippers and attaching them to your robot.
Create the threaded rod for your stepper motor like the one on the right.
How to set up your title block: