Ask HN: What is the ultimate gift to a hacker?

My father turns 50 in not too soon. He's an old hacker who learned C in the 80's to be able to do Linux. He was a computer pioneer in our country.

Now he works with security at a big company, and is very interested in cracks.

One idea is to get him a RFID scanner and a lot of tags. Or a complete Arduino set, with everything. Have you given something to a hacker?