Robert Bullock wrote:
If you want a wimpy field, sure. If you might want to maybe degauss a frame
or some monitor you can't get close to easily, something with more power and
rinage might be useful. Plus, you can erase media with it.

I've degaussed frames w/ my wimpy 19" degaussing coil, with the frame in place
(coil is thin enough to slide between frame and cabinet).

*Never* had the need to do bulk erasing of media.

Heck, why buy one, make one if that's all want. An old electric cord and a
junk deguass harness, etc.

Sure, you can cobble anything together. In fact, why cobble anything together,
just use an electric drill or soldering gun.

Personally I prefer to drop a $20 on a commercial product that was intended for
this purpose. Just giving the OP additional options other than a (what I
consider) an ill-suited item such as a bulk media eraser.