Here is a feedback following the survey launched 6 months ago. The idea was to ask the makers and apprentices which future developments in the Shellopan cooperative could be the most interesting for the community.
The availability of different sizes of shells and the possibility of experimenting with a thicker material (1.1mm) collect the most demand. Although I have received a lot of demand for ready-to-use nitrided material, very few have expressed interest in a material prepared with long nitriding recipe (although the PANArt licensed nitriding process seems to have advantages...).
I have received a lot of demand for the supply of shells and this volume can not be supplied with the production that I realize today. The limit does not come from the production tools but comes from the choice of steel, all the steel are not equal (the standard DC04 is not a guarantee of quality, the tolerances of the norm are too wide, it is by example frequent of having a DC04 with DC05 characteristics). The level of knowledge of the links between the physical / chemical characteristics of the steel, the impact of nitriding, the most appropriate tuning technique and the timbre of the final instrument is not yet sufficiently developed.
I am sorry if I could not answer all the requests, I decided not to compromise on the choice of the material because I personally use the same steel as the one I share. The arrival of other manufacturers of shells should make the market more fluid but I can only recommend to any buyer to ask for the real characteristics of the purchased steel or shell (physical, chemical, thickness distribution, depth of nitrided layer...).
I am currently working on the production of the 6th Shellopan shell batch, always with 1mm steel and a deep drawing method optimizing the thickness distribution (you can have more information on the fablab page of the shellopan website : http://www.shellopan.fr/index.php/en/our-fablab ). For the 1.1 mm steel, I will have to produce my own steel (25 tons minimum). Such a volume will only be feasible if I can obtain guarantees concerning the physical and chemical characteristics of the material. This warranty is for the moment impossible to obtain and I would inform you of any progress.