Made this after seeing all the comics about Bowsette.

The crown is made up of two pieces. The bottom can be worn as is. The top part fits nicely into the bottom piece. I was originally thinking that this top piece could be fitted with fabric stretched over, for an even more regal look.

It measures approximately 6.5 in x 6.5 in x 4.25 in. The base is 4.5 inches in diameter. It can be scaled up or down to fit pretty reliably. Don't forget to use supports.

Just print it up and give it a royal paint job.

UPDATE: Due to popular demand, I added another size .stl out of the box which is smaller and more appropriate for Boosette. I also added separate files (in both the regular and small size) for the eyes and top sphere to be printed separately in different filaments. The smaller crown measures approximately 5 in x 5 in x 3 in with the base being around 3.75 inches in diameter.