Vary diameter of tapered beam

Hi all,

I'm trying to create a tapered, hollow cone component and then vary the diameter in an optimization. So far, I've tried 2 methods.

1) Using a PBEAM/PBEAML with stations to create tapered beams. However, with PBEAML, it says I can't create a design variable property relationship with a PBEAML when it has stations. So I'm now trying to use a PBEAM with stations. However I can't find documentation of what the PBEAM_CARD... means in the editing panel. Does anyone know where this documentation is or how to set up a tapered beam as a PBEAM?

2) The second way I've attempted is creating a 2d shell of a cone. I can't directly set the diameter as a design variable, as the only available dimension to set a desvar to is the thickness. I was thinking I could try dimensioning it and creating a parameter for the diameter that I could then vary in an optimization. Does anyone know if this could work or how to do it? 

Thank you in advance!