IWC currently make most on ther own cases with some exceptions like the ceramic cases (originally Metoxit and Kyocera mentioned as the current supplier but what of the metal cases?
If we ignore those cased elsewhere, Cresarrow in the US and the small number of Japanese Isomura cases who were IWC's case suppliers?
Markings on the gold cases provide some information see Solving the Case which give Jules Blum, Eggly & Cie and Wyss & Cie.
Other early case makers used were Schneeberger-Calame, Borgel, Huguenin Freres & Cie, Kramer, Gruber & Co (became Berthold & Co) and Calame & Droz.
No doubt a look through the ledgers (where some of the above names came from) would provide other suppliers.
There has been mention of Staybrite but I'm not sure if they were a case maker or just supplied their steel to the casemaker with the proviso that the cases were marked "Staybrite".
Later on the patents on the Aquatimer cases provide the case maker as Ervin Piquerez.
Does anyone know of other case makers?
Cheers from the cellar