Request some new materials

[hzhaut]

Thank you for this wonderful implement.
I am writing to inquire about some material files for the following :
Iron (Fe) with a density of 7.874 g/cm³
Tantalum (Ta) with a density of 16.65 g/cm³
Platinum (Pt) with a density of 21.45 g/cm³
Barium (Ba) with a density of 2 g/mL

And
Does anyone know how to generate new materials? I have read a lot but have no idea, is there any feasible way? I can pay something for this, please.

Hood