That design looks more difficult to work with than the half-gallon and quart containers that we get in most of the United States (those are waxy cardboard rectangles with square bases and peaked tops), but a lot of people have used them for molds to make block-y things, whether literal blocks, candles, or something else. The waxy coating on the inside made everything easy to remove.

Those, though? As long as there's no smell left, I might suggest just using them for storage. They look well-made for anything from oil to beans, since they're not going to let air or light in.

I can't find the specific episode (probably because they eventually re-run everything on YouTube, so it's hard to guess the seasons), but America's Test Kitchen recently did a thorough spot on sourdough starters. The closest I can find is recipes on their website, which probably served as the "source material" for the aired segment. While I don't have much personal experience, the "master plan" and "myths" articles both look solid and don't require a subscription.

I don't think that I've stumbled across that, but scraping through my notes on various open source projects, here's what I can find (other than Opendesk).

• Mozilla's Open Source Furniture: You'll need the Internet Archive to snag the ZIP file.
• The Nell Desk: I don't know if it ever made it to GitHub as promised, and again, the Internet Archive will get to the media to know what's going on.
• Ronen Kadushin's Open Design: It's non-commercial-only, if that impacts anything, and not really "furniture," but I might as well share whatever I have...
• Apparently, not even the mighty WikiSeat is invulnerable to bit-rot.
• SketchChair is definitely not a wiki, but generates custom CNC-cut furniture designs.

I also have a reference to something called "Simplified Building Concepts," but the only reference that I can find is this monster of a blog post giving an overview.

I'd love to see the actually-intended site, though.