Helical sweep with variable pitch vanes

Here's my issue, I am designing a part with a helical sweep where the pitch varies from 1.33 to 4.6. This part is no problem, the issue is we want to be able to mold this part and as you can see in the picture the vanes wrap around on themselfs. I think if I could keep the vane perpendicular to the asis it could be moldable. I've tried this using both helical sweep and swept blend to no avail.  Thanks in advance.