Brett describes the construction of his rig here:

The camera support bracket is constructed out of 1-inch by 0.5-inch aluminum bar stock. I machined several different lengths and drilled many through holes and threaded holes at 0.5-inch intervals. The camera sits on a 0.25-inch aluminum plate Swiss-cheesed with holes. The result is a somewhat modular system that can accommodate many different arrangements and set-ups. The camera rig is in turn attached to the overall set structure, which is a commercially available aluminum extrusion system called 80/20. This extrusion system is the backbone of the whole set-up. The visible set and the camera set-up are both attached to the extrusion framework, so everything is integral and quite resistant to jostling. Another important factor with all of the mechanical movements (the focus puller setup, the geared heads, and the dolly track) is to have all of the components biased in the direction they will be moving before you start animating them. When you are returning to the start point, go well past the start point, and then go forward in the intended direction, stopping at the start point.

[Figure 4.19] A set from Lucas Wareing’s film AVA. (Courtesy of Lucas Wareing.)

On a larger set, your camera track can be built to move through the set itself to create a trucking shot that is level with the ground. (Although in terms of scale this would be equivalent to a camera on a tripod trucking through a real set.) This was the approach taken by a former student of mine named Lucas Wareing on his student film AVA, made at Emily Carr University of Art + Design in Vancouver. For one particular long trucking shot in the film, the script called for an establishing shot moving through a large set, with a puppet sleeping at the far end and the sun moving across the sky (Figure 4.19).

[Figure 4.20] A wooden camera track. (Courtesy of Lucas Wareing.)

The camera track itself was relatively simple, just consisting of long, flat pieces of wood (Figure 4.20). Two long, rectangular pieces are glued to a flat base, and the tripod head is affixed to a smaller piece of wood that fits snugly inside and can be slid back and forth. The track was designed with additional pieces that slot together like a puzzle so that as the camera moves forward and reaches the end of the track, more pieces can be added so that the move can continue (Figure 4.21). This also helps conceal the track at the beginning of the shot and is created in steps outside the camera frame. This solution was also used because the shot included the camera tilting upward, which may have been easier to achieve with the camera mounted from below rather than above. The camera was moved forward by hand on the sliding track, and about midway through the shot the camera also began to tilt downward while still moving forward.

[Figure 4.21] Taking the camera track apart. (Courtesy of Lucas Wareing.)