About
Pentachoron (also known as 4D Simplex/5-cell) is the simplest possible convex 4-polytope. It contains 5 vertices, 10 edges, 10 faces and 5 cells/3D faces (tetrahedra). For a better understanding of what this figure actually is, let's make simple comparison:
0D point → 1D line → 2D triangle → 3D tetrahedra → 4D pentachoron

Printing tips
It has low contact surface area, so it's highly recommended to use some brim.