For designers, the case is approved is the happiest thing. I believe he has also gone through a lot of efforts to succeed. Of course, you should celebrate it well, but I can give you some other suggestions:
First, although it is a celebration banquet, it is a banquet for everyone, so I still think it is not necessary to give him a gift at this time. You can give him a surprise in advance or later.
Second, if you give a gift, it is still mainly festive. You can give him something he has always wanted. This mood will definitely make him very happy.
Third, give him a commemorative creative gift. You can make a real doll of him, a realistic and cute image, and make him look successful or hard-working, so that he can leave a commemoration. I think it will be very meaningful. You can also give him a couple color-changing cup. The cup with your photo will accompany him through every design process.