I saw that RaspberryPi.org had an article on JPL Open Source Rover. In the comments section, there was a comment by Daniel Perron (who had also commented on this project page) mentioning Sawppy. I think Daniel should have a project page for his own Sawppy but I haven't seen one under his Hackaday.io account.
Which is a shame, because his rover is making good progress and his work totally deserves attention. So I'm going to draw attention to his build on my Sawppy page here.
Here's a scaled-down copy of the image he linked from his RaspberryPi.org comment. From this picture I can see a few changes from my design. The biggest change is in the structural beams. Daniel is using something other than the Misumi 3-series 15mm extrusion that I used. I'm curious to see how well these beams work. Their uninterrupted square profile should make Daniel's Sawppy more rigid than mine, and more rigidity is always good.
And here's his YouTube clip showing his travel motor turning a wheel under control of his own servo control code.
I'm super excited to see another Sawppy taking form. Your rover looks great, Daniel! Great job and I look forward to seeing your future progress.