The Platonic Solid Tool is located in Create > Primitives. This tool is very easy to use and can really speed up the modeling process. A platonic solid, as denoted by Euclid in the last proposition of his seminal mathematics textbook The Elements, is a polyhedron whose faces are all congruent regular polygons, and where the same number of faces meets at every vertex. The best-known example is a cube (or hexahedron) whose faces are six congruent squares. Platonic solids are often used as dice in role-playing games, so if you want to make a D4, D6, D8, D12 and D20 easily, this is the tool for you!

The Shape pop-up menu on the numeric panel controls the shape of the object. It gives you seven primitive shapes to select from.

Tetrahedron - the simplest of the platonic solids made with just three triangles.

Cube - the best known of the platonic solids, otherwise known as a hexahedron.

Octahedron - an eight-sided object.

Cube octahedron - Although this panel is named the Platonic Solid Tool, a Cube octahedron is not actually a platonic solid

Icosahedrons - a 20-sided object made with triangles.

Dodecahedron - a 12-sided object made from pentagons

Icosidodecahedron - This one isn't a platonic solid either folks!

You can drag the center position handle to move the shape, and you can drag the outer bounding box edges to resize it. You can also use the numeric window to accomplish these to options.