No matter how many groomsmen you have, you need to purchase thank you gifts for each one. The easiest thing is to buy them all the same thing, and something they can use during the weekend of the wedding. Provided all the gifts have the same approximate value, though, there’s no reason why you can’t by them different and individualized presents if you prefer.
Traditional groomsmen gifts: flasks, cuff links, toiletry bags, personalized golf balls and tees, beer steins, lighters, money clips, Swiss army knives, and pocket watches.
Other ideas: concert tickets, sunglasses, sports jerseys, and gift certificates to their favorite restaurants.