Groomsmen gifts need to be either funny, personal, or useful. Most people (excluding
@RedDenver ) don't use mugs or steins. I got my best man a stein and it sat on a shelf collecting dust, but probably the worst part of it was the impersonality of the gift. Unless you know your groomsmen really want steins, giving them the same old traditional gift will be super underwhelming.
So here are some interesting/fun gift ideas, that may be practical and/or useful:
Customized Bobbleheads
Customized Bottle Openers
Leatherman knives/tools (can even get them engraved) or
other customized knives or
even a Machete
RaspberryPi preloaded with some kind of groovy software.
If you all have a shared hobby, maybe something along those lines.
Maybe the most important thing to do, whatever you give them, is include a personal note in each box telling each guy why you picked him to be on your wedding team. I really, really wish I had done that, but I got married at 21 and was more interested in the party than anything (and I was quite a bit focused on the bride).