I've played around with the charts, what chart are you referring too?

after playing around it seems the only way to me is to use lines to make the shapes, i've written a small test that makes the triangle like in the sheet i attached, then group it to resize it easier, but if the shape has to be auto generated may as well generate it each time.

Hrmm Actually thinking about it, if all the shapes are going to be the same, you could create the autoshapes using the lines, group them, add them to the autoshape collection? ( think you can do this) then when the user puts in the dimensions, draw the shape according to the dimensions given using the autoshapes that you just created?