I think you may find this interesting:
I've also ordered one. [Thanks, Alec]. The reviews suggest it's nowhere near as responsive as an Ebow but it costs less than half as much so I thought I could at least have fun comparing the two.
🤔 Interesting little thing but very expensive for what it is, I think.
You could probably make something yourself that does the job well enough! Might even have a go myself one day 😉