The mechanical body of our bot, as with many in this class, ended up taking the form of a multi-tiered tower made of laser cut duron. Note that our bot was confined by a size requirement of 11"x 11" in horizontal dimensions and 12" tall.
The single most important level in our bot is the bottom level with dimensions of 7.5"X 11". As can be seen in the image below, this level serves three major functions. First, it houses and supports the entirety of our drivetrain. This is mainly achieved through laser cut mounts and a "tongue and groove" mating system. Second, it houses all four of our tape sensors. This is achieved by placing the sensors in small rectangular cutouts within the bottom level, and then supporting them through laser cut mounts bolted together with screws. Third, the bottom level houses all three of our IR sensors (one on the front and one one on either side). This is again achieved through laser cut mounts and the "tongue and groove" mating system. Together these add up to a fairly complicated, but integral, bottom level to our bot. Note that the bottom level also house our two batteries, however this achieved using zip ties and was not expressly designed for.
Our bot then incorporated two middle levels for storage purposes. In the form of 7 in. diameter circles, these middle levels added rigidity to our bot while also giving us a place to put a lot of our components. For instance, the bottom middle level of our bot housed all of our circuits, and although not the most organized of levels, tape and zip ties provided enough organization for this level to be reasonably discrete and still malleable. The upper middle level of our bot housed our stepper motor.
Finally, our bot incorporated a token delivery mechanism. This can be explored in more depth through the Token Delivery Page, however this basically consisted of two 7" circular levels, one rigidly attached to the stepper motor and therefore able to spin 360 degrees, and one rigidly attached to the bottom middle level with a slit for chips to fall through and a ramp to funnel them to the bins.
Note that 1/4" Threaded Steel Rod and Hex Nuts were used to hold the various levels together and make sure that our bot was rigid.
Again, the most important step in building this mechanical assembly was a full CAD model. Having a full model hashed out before assembly meant that we minimized the number of problems we ran into while building, and our mechanical design was robust enough to only require a single change during physical assembly (we had to sand down the photo transistor ports because they kept getting stuck under the force bins). Seen below are various screenshots from this model, namely a top view of every level within the assembly and a few views of the complete bot. Again, the full CAD model can be found in Jamie Young's Coursework dropbox, and a STP model displaying the full geometry of our assembly can be found in the Final Design Section.