In his article of December 23, 1776, Paine refers to the "summer soldier" and the "sunshine patriot." The term "summer soldier" is one still heard today. Both of these are metaphors akin to our use of "fair weather friend." Summer and sunshine are metaphors for the idea that it is easy to be a soldier when things are going well, but this kind of soldier "shrinks" from serving his country when the going gets rough. There is, of course, a perfectly good literal basis for this metaphor, since it is far easier to be a soldier when the weather is warm. You do not have to worry about slogging through ice and snow or whether your shoes have holes in them.
Here is an extended metaphor Paine uses in his article of January 13, 1777:
It is surprising to what a pitch of infatuation, blind folly and obstinacy will carry mankind, and your lordship's drowsy proclamation is a proof that it does not even quit them in their sleep. Perhaps you thought America too was taking a nap, and therefore chose, like Satan to Eve, to whisper the delusion softly, lest you should awaken her. This continent, sir, is too extensive to sleep all at once, and too watchful, even in its slumbers, not to startle at the unhallowed foot of an invader.
This is a metaphor and a form of personification. Picture England and the colonies as people. England has been sleeping, Paine says, and it should not make the mistake of believing the colonies have been sleeping, too. England has taken a stand against the colonies that suggests it thinks the colonies will do nothing in their defence. It has "whispered" its stand, so the colonies will not wake up and do something. While this rhetoric is addressed to England, it is also meant to arouse the colonists, who do not wish to be thought of as sleeping.
There are many other metaphors in the collected articles. Perhaps you can find some, too. Good luck!