I found a video of one being used.
You have to be careful and know what you are doing,
getting constant feedback from the lady.
It can be an awesome new experience for a lady,
but if a dude is clumsy or over zealous he could injure her.
The proper attachment and toys made for Vac-U-Lock are a must.
Something homemade would certainly be dangerous,
and it's not as noisy if you don't tape a mic to it like the guy
in the video did LOL
http://www.xvideos.com/video8222100/...cking_machines
This one is with the drill attachment.
http://www.xvideos.com/video8379951/...ucking_machine