Make a cabriole leg in 5 minutes using this special trick and router hack.

One place you can purchase the over-sized door knobs:
3" Wooden Ball Knobs / Doll Heads
https://www.amazon.com/Wooden-Ball-Kn...

TIP:
Keep in mind, the router bit extension is NOT required. If you make a slightly smaller dome (1/8" or 3/16" less tall), you can raise the router bit high enough to line up with the top of the dome. And you can simply screw the dome to the router plate.