Tetrahedrons

Size: 4; Number of spheres: 20

These pieces make nice puzzles to be solved by hand.

Size: 5; Number of spheres: 35

Size: 6; Number of spheres: 35

Size: 7; Number of spheres: 84

Size: 8; Number of spheres:120

Size: 9; Number of spheres: 165

Size: 10; Number of spheres: 220