Our sanctuary always tries to reuse every day items to modify them in enrichment tools. This is how the idea came up to fill up old socks with some dry food (cereals, pop corn, dry fruits, peanuts, etc) the chimps love!
Tody, we filmed JAC and you will see that he doesn’t care about opening the knot on top of the sock : he rather bites the sock open to get the treats…
https://youtu.be/_B-Tex_8tIQ