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.
No frills speaker manufacturers
What are some speaker companies that put all or most of their build budget into parts and design function and none or hardly none into aesthetic? If there was no wife acceptance factor and you didn't give a hoot about how they look what speakers would you buy?