I have been trying to design a valve body that is made by casting. I have tried using loft in surfaces and create a internal surface, then thicken the surface to get a solid. but the result are not matching the print. My question how can one design a complex shape like valve body casting using solid works and have control over the filet sizes, etc.? also something else which is important in modeling this design is that the flow cross section should be consistent through the valve. meaning the flow cross section area should be equal to area of a circle with 2" diameter. so when height of cross section is reduced the cross section becomes and eclipse.

Thanks,