So what exactly is the bore size of the Werder? Roughly 0.460" if it's an 11,5mm? (Closet Lyman gets is 0.459") Or is it regular Mauser size? (0.446" seems to be the H&I Lyman default.)
If doing a custom job, it seems the Lee push-through type bullet sizer that screws into a standard reloading press would be the easy route. Basic lathe work, but it requires pre-lubed bullets. I was surprised at how well the 0.358" Lee bullet sizer worked, given the rough finish of the conical area leading to the finish diameter. But no metal build-up or shaving at all! With just a little more work, the conical base forming step ought not be a huge leap.