As far as I can tell, there is no way to tell S3D the density of the material you are using. Why not?
It asks filament diameter. It asks $/kg. And it assumes a density based on what material you tell it you are using.
The problem is, not all ABS is the same density. Not all PLA is the same density. Not all Nylon is the same density.
Furthermore, I can't give it a density for filaments that have no radio button. No Ninjaflex, no filaflex, PC, no PC-ABS alloy.
I can't get accurate weight estimates, and therefore accurate material cost estimates, without being able to specify material density.