No frills speaker manufacturers

Kit speakers are precisely what you want.  Look up CSS Audio, GR Research, Madisound, & Meniscus.  Some even come with flat pack (wood already cut to size) and/or preassembled crossover boards.  You can not even come CLOSE  to the same parts quality any other way.  Not even close.

Tekton Design to your first question. To your second question, I’d probably buy something from Focal, Sonus Faber, or Wilson. I’ve owned two pairs of Tektons and I likely won’t buy another pair because, to me, looks do matter. I’ve liked the sound of most of the Tekton models I have heard but not the looks.

Vandersteen’s cloth covered models and ATC studio series.

GR Research, absolutely. Danny Richie is an excellent designer, and offers his loudspeakers as kits only. However, as noted above the enclosures are offered as flat packs (and even fully assembled and painted or veneered if so desired) by closely-affiliated woodworkers. Watch his videos on YouTube (easy to find. Just do a search for GR Research) to learn more about what he offers.