I've put food on skewers for Harley before. Here's a photo from the old apartment.

Although we didn't move this perch when we moved the cage to the new house, Harley rarely sits on it anymore. Skewers were often ignored in the apartment, but they're almost always ignored in this spot now. So I needed a new plan.
The thing is, Harley can be pretty lazy when it comes to — well, anything. He'll work pretty hard for a snack, but some of his favorite toys are ones he stands on and quietly chews to bits. This is not a bird that hangs upside down from one toe, screeching and throwing toys around. He's much more likely to sit on a perch, one foot tucked up, and doze the day away. That's probably why we get along so well.
Still, some activity is good. So I persevered, and finally managed to get the metal pole on Harley's tree stand angled in the correct way, and hung the skewer. Success! I found the sweet spot about two weeks ago, I've given him a skewer almost every day since, and he's played with the toy every day but one. These next four photos were taken on four different days:

That nondescript brown thing hanging from the bottom of the skewer in all four photos is a coffee filter with some of the so-called food I give him every day tucked inside. The food is a combination of lightly sprouted grains and seeds, cooked beans, and minced vegetables that he usually ignores while looking for peas, pomegranate arils and bits of apple. Surprisingly, it almost seems like he's eating it when it's "hidden" in the coffee filter.
Let me clarify: the game is definitely "I MUST REMOVE ALL THE LITTLE BITS FROM INSIDE THE BROWN PAPER!" But it seems possible that he's actually, occasionally, swallowing a molecule or two of food while he's playing. This is not
swallowing inhaling cheese, mind you — it's more like osmosis. But I'll take it.
He also enjoys playing with the vegetables, which generally entails tearing them into little bits. But sometimes he'll take a bite, chew it up in his beak to drink the liquid, and spit it out again. His favorite seems to be zucchini, but sweet potato and the greens usually get bites taken out of them as well.
Bruce called me up today to tell me about an article on the health benefits of peanut butter. See "
For love of peanut butter" by Nanci Hellmich, in USA TODAY. The article states "It's an almost ideal food when eaten in moderation because it's rich in protein, high in healthful monounsaturated fat and relatively inexpensive."
Of course, we all know Bruce only mentioned this article because he wants to give Harley more peanuts for dessert. A LOT more.
Harley doesn't actually eat walnuts, but occasionally, they make pretty good toys.

If he actually ate walnuts, we probably wouldn't give him a whole one in one sitting.
Well, Bruce might. But Bruce is very weak.