I sent to make some pieces to some workshop specialized in stamping or punched pieces. It is a metallic (SS316l) ring with a "U" shape (wall thickness=0,1mm=.004"). Medium diameter rounds 10mm (.04"). Curve radius of "U"=1mm(=.4"). I paid a half in advance. Now he called me to give me back the money because he failed because the material is so thin and gets broken, then he offered me me keep working on without warranties of succes. I asked him keep on working under my responsability and cost of the advanced money. Any help please..