The challenge was for the bears to optimize their tongues and claws, like how they would forage for wood within tree trunks and branches - so some of the blocks had an intricate maze drilled in them, with the treats hidden and stuffed in impossible corners. It was fascinating to watch how the bears used these two body parts to manipulate their way to the food. Usually it involved using the ends of their claws to scrape the food out, and then licking the claws.
I think working with destructive macaws helped a lot. As I said earlier, the challenge with enrichments is the durability: will it keep the animal interested long enough before being destroyed? Some of the blocks lasted almost an hour which I think was good enough.
And one thing we found out - male sun bears have twice the strength of females! Bermuda lost patience within the first five minutes and proceeded to rip our block apart with ease. Have to keep that in mind next time….