This is a www.thingiverse.com file. Joyce found it when I told her I needed more than 12 hour notice for holiday related prints.
muzz64 provides two sizes, 50 mm and 65 mm, which fit the Kinder Joy and Cadbury eggs very well. He also provides the formula to change the sizes. Pretty nice guy. On my Prusa i3 Mk3S+ print time for the 50 mm was about 1 hour and 39 minutes. For the 65 mm version print time was about 2 hours and 17 minutes.