In 2015 a volunteer got really excited when he opened my trunk and called for a supervisor to ask, "That can't have this, right?" The supervisor seemed kind of annoyed and said, "That jumpstarter is fine, dude." I can't imagine why someone would think a mallet was a problem, and surely a few thousand of them go through the gates.
I snuck a French press in every year I went. Hide it well and you'll be fine.
Ditto on the french press - best simple solution for fresh coffee if you have a way to heat water. Don't bring glass beer or liquor bottles or whatever, but carefully hiding something like that shouldn't be a problem if you don't have a non-glass alternative.