These were originally designed by Kendrew and made up in the Cavendish workshops and later (from 1958) in the MRC Unit's own workshops. By 1960 they were manufactured by Cambridge Repetition Engineers Ltd., several being sold to other laboratories mainly in US. They were frequently, though unofficially, known as Kendrew models. Correspondence with MRC and others August 1963 - December 1965, provides historical information on the matter.