I don't want to derail the conversation, but you intrigued me. I'm always on the hunt for different materials with different properties, but I do get tired of the high price of the exotics. I'd love something less crystal-brittle than PLA (but still as easy to print -- no enclosure means ABS is generally a pain) that was also sanely priced for general use. The "flexible PLA" sounds good, but I'm curious what it actually is. Quick Amazon search turned up something (WYZworks Soft Flexible PLA) claiming to be flexible PLA with 85A Shore hardness, which is NinjaFlex territory (so I suspect that it is really TPU, possible with just enough PLA in it for marketing purposes?). I can print that fine, but it sounded like you were talking about something stiffer than that. Maybe some of the "PLA Plus" materials? Do you have links to stuff that's worked well for you in the past?