As we have gone along we have tried to get feedback from various constituencies: people who never took calculus but are curious, people who teach it, people who teach less-advanced math but are interested in adding in these concepts earlier, and so on.
The first advice we got from people focused on the teaching aspect was that it would be too hard to support electronics, 3D printing, and other hands-on activities all in the service of a calculus class. The suggestion was to focus on just one thing and to be sure that the ideas made sense even if someone were just reading about the objects and seeing them in photographs. Otherwise we need to explain each technology used before getting into the calculus part, which admittedly can be a distraction. Our original approach, though (of making things a variety of ways) may still be a valid way to go for schools with an extensive makerspace, and we haven’t completely given up on that.
We were grateful that Yue-Ting Siu, Assistant Professor in the Graduate College of Education at San Francisco State, took a look at some of our early models. Dr. Siu is interested in how best to teach the visually impaired. Obviously 3D prints work best for this constituency (compared to building electronics), and her suggestion was to thing about how to add gridlines and other orienting material to these plots. We are thinking about the best ways to do that within the resolution and surface finish limitations of a 3D printer, and without cluttering the models or making them confusing.
Dr. Siu also suggested that we think about neurodiversity generally and consider how our approach might help other learners who are not served well by traditional education, beyond the visually impaired. As we note in the summary in the "Details" section, we are very interested in exploring this area further with others who have specific expertise.