about 1.5 inches, and i got 30 of them from one cake, but j's (the expert) were larger, like about 2 inches. then stick your cake balls in the freezer to firm up.
give 'em an hour or two, or four, just let them get nice and firm.
then melt some chocolate, almond bark, or candy melts in the color of your choice. take a lollipop stick (mine were 6 inches long), and dip it about half an inch into your melted goodness. then, gently, using a swirly motion, poke the stick about half an inch or more into your cake ball. once all of the cake balls have a stick in 