All machines below (unless specified) would be considered bulky gauge (judging by the sizes of the needles and the yarns these machines can handle). These machines are called plastic because their bodies and needles are plastic. Some sock machines have plastic bodies but their needles are metal. Those machines are on the Sock Knitting Machines page.
Addi, egg, 6 needles
Addi express, 22 needles
Addi Kingsize, 46 needles
Hello Hobby, 22 needles
Jamit
Mattel, 16 needles
Sentro, 22 needles
Sentro, 40 needles
Sentro, 48 needles
Singer, 20 needles