It is to be believed that Ateliers Cropsy has been founded by Alerion around 1948. They resided in the 15th District of Paris. This manufacturer concentrated its production on premanufactured "wooden" buildings. In fact the components used were wood (for the base), hardboard (for the walls and roofs) and rhodoid (for the windows). All models do have architectual looks. They were constructed quite accurate and reflected true models. It is no doubt that the production of Ateliers Cropsy buildings can be considered as an artisanal production. All buildings were manufactured on a 1/87 scale. Due to this choice the buildings look quite large compared with model trains for H0 gauge.

Ateliers Cropsy explicitly have chosen to create French buildings. There were models for almost every French region, such as the Savoy, Normandy, Brittany, Bourgogne, Sologne, Provence, Val-de-Lyon and Alsace. A first rare original Cropsy catalogue from 1950 shows only the beginning of an extensive range of buildings. There seems to be another original catalogue from 1952. Collectors do have to rely on catalogues of retailers like RMA, Au Pélican and Baby-Trains to view the entire range of buildings offered. And there seems to be even buildings never pictured in any catalogue.

It was quite obvious that Ateliers Cropsy offered all types of railway structures, such as railway stations, signal boxes, roundhouses etc. There were some impressive models like the railway station "Pont-sur-Yonne", "Venoix" or "Mehon". But, Ateliers Cropsy offered also a wide range of other buildings to create true villages with family houses, garages, cafés, hotels, churches, small factories, coutryside houses. A special series was a range of "modern" city buildings called "Rue Battant". Nowadays the signal boxes are the most easy to find buildings.

Due to their construction materials, mainly wood and hardboard, not all models survived due to humid conditions. Models in good to excellent condition were mainly kept in their original (grey) hardboard boxes. Normally each building should a distinguishable logo on the base. This logo, however, could be lost by usage over the years.

The end of production seems to be around 1962/63. Accurate data need to researched. During the mid to late 1950s German manufacturers, like Faller, Kibri, VauPe and Vollmer were gaining more and more attraction by customers. Their buildings were in fact less detailed than those by Ateliers Cropsy, but quite likely less expensive. During the late 1950s plastic parts found their way to replace more expensive construction materials. Due to the artisanal production of Ateliers Cropsy quantities could not reach the same level as of those German manufacturers.