Home units/suitcase cutters - These were consumer units that were small, portable and self contained. Recordings from these machines are of relatively low-fidelity. Home units generally included a built in amplifier, cutting arm, playback arm, microphone, and radio. They were used for recording radio programs, audio letters, or general personal recordings. Many of the cutting units for these modes were made by General Industries, who sold them to companies like Wilcox-Gay, Airline, Silvertone, etc who installed them with their own amplifiers, radios, control panels, etc. These units generally used a generic crystal cutter head. The crystals in these cutter heads would deterioate after an extended period of disuse, so most unrestored units on the market will not record. However, Gib Epling at www.West-Techservices.com, offers affordable restoration services for these heads webmail.
Some examples:

             
Wilcox-Gay Recordio (1940)                                                                  Silvertone Suitcase Model