Musicraft was a San Francisco company established around 1967 by Bert Casey (President) and Arnold Curtis (Senior Vice-President). They introduced the Messenger range of guitars and amplifiers,  built around a patented aluminum chassis. This aluminum chassis was tuned to resonate at 440Hz and extended throughout the guitar's length - allowing a thin fast playing neck. The fingerboard was located outside the sound chamber for unobstructed access to all frets. The Messenger had electronics equipped for both mono and stereo signals and the bass and treble signals could be amplified separately. Finish options included yellow, red, black and sunburst and there was also a 12-string and a fretless bass model.

Source: Musicraft Creates New Guitar Neck. Billboard. 13 May, 1967. Page 62.

Source: Musicraft Messenger catalog 1967