First of all, big thanks to Hoff 07 for coming up with the great idea of using a reciprocating saw for doing this achievement in literally no time at all!
As I don't have a reciprocating saw but still wanted to something similar without much effort, I came up with this.
Once again, I'm NOT stealing his idea, I'm giving him full credit, this is just another method that probably more people can do as I'm using an electric mixer with a little bit of cardboard and duct tape. :)
I'm getting anywhere between 500 and 1000 per minute with this method, so it's not quite as efficient as a reciprocating saw, but still good for almost no effort at all.
Guide for setup:
I used a regular electric mixer, you could probably use similar household objects too.
Remove one as you'll only be needing one.
This is what I used to make this work: Scizzor, Duct Tape, little bit of cardboard.
I then put the cardboard like this.
Some duct tape.
How it looks on the other side. (Use more duct tape if it seems loose)
The finished product:
Either simply hold it while it autostrums on your guitar or duct tape it in some way that you don't even need to hold the mixer!
Before you downvote, Please leave a comment as to why, or how I could make this solution better!