Prince Tsushinkogyo Co. Ltd.  (Prince Telecommunication and Engineering) was founded in 1950  in Nagoya, Japan. They concentrated on making tuners and solid state musical instrument amplifiers which were sold under the Prince brand names as well as others (such as Memphis). The company began to use the Arion brand name in 1980 and began making guitar effects pedals. The company's fortunes declined in the 1990s and by 1997 Arion was sold to the Ueno Kaihatsu Center, who continued making pedals and tuners, but discontinued the amplifiers.
 

Custom classical guitar maker based in Old Town Albuquerque NM, USA. Also makes steel string guitars and ukeleles.

The McKinney School of  Music in Peoria, Illinois sold McKinney branded acoustic and electric lap steel guitars and amplifiers made by Valco in the 1940s and 1950s. Often these were sold as a matched pair.

Source: Vintage guitar magazine: 7 vintage sleeper amps (July 2017)

Joe McKay started making acoustic instruments in the mid 1990s in a shed next to his house. He started by studying violin making with the late Robert Rife. McKay combined this luthiery training with the principles of engineering and physics learned from his college education to develop acoustic guitars with original bracing patterns and hand tuned tops. McKay Guitars produced a limited number of custom handmade guitars each year - but circa 2018 the website was inactive.

Source: McKay Guitars website (archived 2013)

Andrew White is a West Virginia luthier with nearly 20 years experience. He currently offers four distinct series of acoustic guitars: Luthier’s Collection, Deckers Creek Series, Signature Series, and Production Series. The Luthiers Collection is hand made by Andrew White as custom one of a kind models with luxury features. The Deckers Creek Series is designed by Andrew White using traditional designs with Andrew’s attention to detail and craftsmanship. The Signature Series uses White’s revolutionary body styles and traditional bracing. The Production Series guitars are more affordable being factory manufactured guitars (to the same specifications as the Signature Series).

Source: Andrew White Guitars website (8 March 2018)

Tom "Howard" McCormick was a Phoenix based electronics wizard who started making custom amplifiers for Duane Eddy in the late 1950s. McCormick's Howtronics company introduced a Howard brand of amplifiers which were some of the cleanest and loudest amps on the market at the time. These Howard amps had closed back cabinets and 15" JBL speakers - like the Fender Showman which appeared in 1961.

McCormick also introduced a range of Howard brand electric guitars. These had radical futuristic designs and used some unconvential construction features like fibreglass necks and reverse headstocks. These Howard guitars of the late 1950s and early 1960s are very rare. Howard even made a double neck model for Duane Eddy.

Paul Tebbutt founded Pilgrim Guitars in the 1970s in Leicestershire, UK as a small scale producer of acoustic guitars. Production stopped n the mid 1980s. In 2009 JHS and Paul Tebbutt joined forces to bring the Pilgrim brand name back to the market. The range now includes Pilgrim banjos, G banjos, tenors, ukulele banjos, bluegrass models, resonator and long neck models. There are also Pilgrim Mandolin, Mandolas and acoustic guitars.

Source: JHS Pilgrim website (1 March 2018)

Mark Burnet studied stringed instrument making at Anniesland college in Glasgow and then worked with a classical guitar maker where he learned traditional Spanish construction techniques. He then studied at the Instrument making school 'Centrum voor Muziekinstrumentenbouw' in Puurs, Belgium. On his return to Scotland he established his own workshop in East Lothian where he makes acoustic and classical guitars by hand, as well as offering guitar repairs and set-ups.

Source: Mark Burnet Guitars website (28 February 2018)