In fact, people in middle age are particularly prone to emotionality. You don't have to give your father a gift to make him happy. You can go out with him on weekends, sing songs, and play chess on weekdays. These can relieve his pressure and let him feel your love for him at all times, so that he will feel better.
If work is not going well, he will definitely be in a bad mood. It can be seen that your father must love you very much, otherwise he would not force a smile in front of you. If he is in a bad mood, it must be because of the pressure. Give your father a magnetic bracelet. I heard that this kind of fatigue-relieving bracelet is very popular now. When your father sees the bracelet, he will understand your intentions and will naturally be happy.
You can give a crystal music box. When you are in a bad mood, listen to the soothing music in the music box. Even if you can't get better completely, I believe you can get twice the result with half the effort. You can also print photos of your family on the music box so that your father can always feel the warmth of his family. The effect should be better.