Sand Blasted Pyramid With Decorative Inner Chamber For this project, you will need an additional mold.. Mold #92 will give you the sloped pyramid blocks, but you will also need Mold #96 for the straight walls and decorative pieces for the inner chamber.. Cast the #92 pyramid mold 19 times and cast the #96 basic block mold 10 times to build this pyramid.. If you don't want to buy an extra mold ...