Egg shakers are underestimated by unknowing individuals like myself that figured they might just be an interesting substitute for, say, a hi-hat.
The kind of co-ordination needed to get the rhythm you want without adding beats and accents that shouldn’t be there is quite different from what I’m used to from the drumkit. Also, are you going to make these eggs sizzle, swirl, snap, or pop? They offer a whole range of sounds and attacks that take diligent practice and effort to learn to control them.
It already begins with how you hold them. In the end, holding your eggs is one thing, but knowing what to do with them a whole different story. (Both true and pun fully intended.)