What should I buy for an Abyssinian that needs constant activity?

A cat wheel is the obvious first purchase - those things actually work for high-energy breeds if you get a sturdy, well-made one (the cheap plastic ones wobble and they'll ignore it). I'd also grab a few puzzle feeders and treat-dispensing balls because you'll go insane trying to entertain them manually for hours. Wand toys with replaceable attachments are non-negotiable too, but rotate them every few days or they'll get bored and stare at you like you're failing at life.