The tax man must have missed your collection. I returned from a Canadian site where I'd been setting up a system and had my toolbox, including a few octal relays in case I had to replace any. The relays were Japanese and I did not have proof that they had been purchased in the US so they charged me the import duty.
The customs officers were being pricks. US and Canadian relations have been mixed far before Trump. When the countries are in a pissing contest citizens crossing the borer bear the brunt. I was next to a guy clearing the Canadian side. He was a shoe salesman with his sample case. They nailed him for the duty even though he pointed out they were all left foot shoes.