Hi, I'm in the midst of testing out my 1st new prop this year. (I'm way behind Melty!)
I linked a utoob video below.
It is a very simple idea using about 4 dollars of PVC, some fishing line and a wiper motor - It can be used for a million things, and it can be used to make several props move at the same time. It may have been done before, if it has let me know, it would make life easier for me.
In the video here I used it to make a blucky dance (a very noisy blucky) - notice at the end of the video the blucky arm falls off
I actually plan on using it to animate a whole row of props, to MM's "This is Halloween" but will not have video of that until after HalloWeen.