How to build a tetrahedra model in HFSS?

It is easy to build a cone model in hfss, but I feel difficult to create a tetrahedra model? could anyone give guidance?

Thanks!

Hi,
you can
1 -- build a Rect. Box with your Tetrahedra dimension
2 -- create four another boxs and rotate them respect to above box in correct angle.
3 -- Subtrace thses four box from First Box.

KMPA