I do tend to catch myself obsessing over tiny mechanical implementation details, and I have to periodically remind myself that they all have to work in service of overall project goals. The primary goal of the little Sawppy rover is to make a DIY motorized 3D-printed Mars rover model accessible to people that would be otherwise excluded by the larger rover. A lower cost to make it within reach of those who found Sawppy too expensive. Fewer parts and easier to build for those who found Sawppy too complex. Which has a side effect of a smaller size for those who found Sawppy too big and bulky.

The smaller size also opened another path that I wanted to explore: not just a little rover, but a cute little rover. Sawppy mostly followed the scale and proportions of Curiosity rover. Most of the deviations came from when I made sacrifices to make parts easier to 3D print. But as soon as I saw the cute rover illustration for JPL’s Mars 2020 naming contest I knew I wanted to make a rover that willingly sacrifices scale fidelity in order to gain physical appeal. This was reinforced when I learned of ExoMy. Which took the designs of ESA ExoMars mission rover Rosalind Franklin, and turned it into a cute rover with a smiling face.

My little Sawppy rover can’t help but look cute next to a full size Sawppy, like a duckling following around mama duck. Rather than putting up any futile effort to fight it, I plan to lean into the cute angle. Aside from just the sheer fun of it, I also hope a cute appearance will make the project appealing and attract an audience who would otherwise be less interested in a mechanically faithful scale model.

From a design standpoint, this means changing around some proportion on the little rover. Adapting counterparts to traits that we humans instinctively associate with young animals. Following ExoMy’s lead, a little rover will start with the following:

• Replace the mast camera assembly with a larger anthropomorphic face as ExoMy did. This is analogous to how young animals have larger heads relative to their body and big eyes on those heads.
• Shorten individual segments of the rocker-bogie suspension, corresponding to proportionally shorter limbs of young animals.
• Wheels that are larger than scale, emulating proportionally larger feet of young animals. However, this is less important than the previous item: once the suspension segments are shortened, the wheels will naturally look larger in comparison even if I don’t make them larger than scale.

But that is only a starting point, there are many other potential ideas along those lines:

• Faster motors and a drive system that allows it to come across as high-energy relative to more sedate “grown up” rovers.
• If some sort of vocalization are to be added, the little rover would have a higher pitched voice.

I expect it’ll take several iterations before I get a decent design for a little Sawppy rover. Lessons learned and incorporated as I go, starting with prototype number one.