I use "cow knuckles" from the butcher, these keep them amused for a couple of hours. You need to examine their poop though. Some basenjis will get the trots. If this occurs- bad idea.
My youngest will gather all of them up and hide them in my bed. Icky.
My first Basenji would hoard and bury them. Amusing. She would have one out and if the other 2 took it, she would simply go dig a fresh one up.
The grab bag at second hand stores have stuffed animals. This kept my first 2 amused. They would eviserate them.
I had one of those "magic cubes" that you stuff treats in and when it knocked about the treats fall out. That lasted about 2 weeks. They figured out that if they broke it all the treats came out.
One of those big yoga balls with peanut butter smeared on it kept 2 of my 3 amused for a couple hours.
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