Hmm, the post shows that the case was designed in OnShape but the screenshot shows that's its an imported STEP file from Solidworks(?). Admittedly though, I haven't used OnShape since they removed the private project options so I might be wrong.
Understandably, OnShape and Fusion360 (the HSMWorks/CAM integration in it is awesome.) is great for startups and hobbyist. But if you're trying to design some large assemblies or things with complex organic shapes, Solidworks is significantly superior in every way (I'm extremely bias since Solidworks is my favorite CAD software). I know the price is a lot for a startup but I highly recommend any company trying to get into the hardware side of things, to stick with the "foundational" CAD software because in the current CAD software landscape, the investment into these software would pay off in less than a year.