So I was watching a video and saw a boing-e done with one hand. They had two identical yoyos, one that didn’t spin or have a string. They stuck the unspinning yoyo in place of their left hand and did their boing-e. so I thought about wether or not you could do any other tricks with that setup. You probably could, but you would need something that wouldn’t fall off a string.
------------------- / String \ | | | | | | [___] [___] *weight* *weight*
Like that. It would just have to be the exact weight of the yoyo within a gram or two.