Hello there?i am engineer and product design,i am very interested with your project,i can help you for make 3d modelling and 2d drawing your casing battery ,i can send format file you needs as STEP,IGES,STL,X_T,DXF,DWG and etc,not just make design but i am understand and expert about manufacture,cnc milling,fabrication,3d printing,so all my design easy to manufacture and prototype,i 'll send good result and hight quality,i am not engineer outsource all jobs and task i do it my self,so we can discuss every time,you want good quality please chat me,you not dispointed,i hope we can work togheter and i am very happy if can help you,Best regard