No. 3: Zero in on what Dad loves
Buying items for a hobbyist can have its challenges, but have faith that you can find something within the realm of Dad's interests. Target his hobby. Does he grill? Does he have a personal home library? Does he jump on his motorcycle to relax?
If you feel confident buying him a grilling tool, a specific book or a new helmet for his motorcycle, go for it. But this is where it can be tricky and he might want to help pick out some of these things for himself.
A gift card might not seem like a very personalized gift, but it can be. Buy him a gift card to his favorite bookseller and write a personalized message about how he can use the credit.
No matter what, a gift that shows Dad that you pay attention to who he is and what's important to him will go a long way.