Closure of the mines.
At the end of the 1960s, the mines in Limburg were closed. DSM (De Staatsmijnen) owned workshops where disabled miners could carry out work, in order to have a sensible daily activity. These ‘WIM workshops’ (Werkplaats Invalide Mijnwerkers) were transformed into social workshops after the mine closure, and transferred to Fonds voor Sociale Instellingen (FSI).
In 1971 the name was changed to Efsi.
One of the activities of the FSI was to continue the model car production of Best box. Initially still under the name Best box, in the 1970s they proceeded to Efsi, a phonetic pronunciation of FSI.
Efsi was moved to industrial park De Beitel in Heerlen. An alloy of zinc and aluminium (Zamak) was used to cast the passenger cars, trucks and buses. They had separate moulds for the plastic parts, from which the wheels, interiors, windows and mirrors were poured. The plastic came from DSM in the form of granules. Passenger cars were phased out in the late 1970s. The maintenance of the moulds and machinery was carried out by Efsi’s own mechanics.