Grabber

Some changes from the original by mathiaspl20.

- The rack is altered to have a hole through its length, so the wire can go through it and be held in place by a knot or tiny screw on the front, so it's easier to attach and adjust on the pipe and handle mechanism I had.
- The rack guide on the back plate is a few mm back, to avoid having the gears teeth grinding against it
- The pipe attachment diameter is changed to 12mm. The original had 10 and 15mm, but neither fit mine.

I used an old guitar string with ball end for the wire. Be sure to use a wire that's strong enough for your needs, but also weak enough so it breaks before the printed parts if someone tries to grab something too heavy. I figured that out the hard way when I used 1.2mm steel wire.