My 4-year-old wanted a glow-in-the-dark sun to go with his Earth and moon mobile stands, so I had him help me design one.

Everything was to his specification (roughly 75mm diameter) but it should scale up well if you want it larger.

The sun prints in halves (internal support recommended as shown, but may work without) and assembles with an IKEA dowel pin that measured 6x30mm (press fit).

The stand prints flat and press fits together. Photos were from version 1.0, but print files have been updated with changes shown in the rendering.