Synonym for "a lot" where each contributes only a little

I'm looking for a professional-context appropriate synonym for the word "a lot", but with the additional expression of "each contributes only a little"

For example,

To fill up that vat you'd need a crapload of tennis balls.

Here "crapload" implies that each individual tennis ball is actually worthless on it's own. Where the vat is big, "crapload" serves to color the sentence.

Unfortunately "crapload" is unprofessional. "A lot" is just colorless. Suggestions?

Solution 1:

Two suggestions:

To fill up that vat you'd need a great many tennis balls.

To fill up that vat you'd need countless tennis balls.

The phrase a great many is often used to convey the idea of an awful lot; with a great many hits on Google books (well over a million, in fact).

Countless doesn't really mean uncountable, but suggests that it might take a truckload of time to count all the tennis balls.

Solution 2:

Plethora ("An excessive amount or number; an abundance") and myriad ("A countless number or multitude (of specified things)" or (now historical) "Ten thousand") are used in such contexts; or you can use both: "To fill up that plethoric vat you'd need a myriad of tennis balls." Note, plethoric does not necessarily mean many, but instead "overabundant or rife", "excessive", or "ruddy in complexion", depending on what or who you apply it to. You could also say an army of tennis balls or a whole host.