Classified subforum - I actually just recently deleted ours, along with some other low-activity subforums. My best guess is that, generally, we're more of collectors or savers or storers rather than sellers. Classifieds subforums do generally work well on automotive forums, which was my initial thinking in starting that subforum.
Subforum for tools that should be made - I'm OK with this stuff going right in the main Homemade Tools subforum. This interesting thread about cutting expensive Vespel guitar picks is a good example. In fact I recently also deleted the Tools in Progress subforum, merged its threads into the main Homemade Tools subforum, and adjusted the description for the main Homemade Tools subforum so that it would be more clear that the main Homemade Tools subforum is NOT only for presenting completed homemade tools.
Miniatures - this is a good point, although miniature content is not particularly common. In fact it was on my list of possible new subforums, but I had to whittle it down to the 10 maximum poll options. I recently adjusted my social media search tools to include more miniature and scale model builds. This scale model Ferrari 312PB build is a good example. It looks like our best bet for content like this will be unique scale model engines, and I have already collected some of those that we will see soon in the main Tool Talk subforum.