How are you planning to fabricate the pyramid? Are you seam welding the 4 radiating edges or is this stamped?
If the pyramid is stamped, you want to use the form feature to create that face. And if that is the case, the part is not too difficult to make from scratch inside sheetmetal.
If you intend to weld those 4 edges, we'll take another tact. Please advise.
Also note that there is not a consistent material thickness throughout. It is better to keep it a solid lump then shell it during the conversion.