Power tools can save a lot of time spent on making the rings. The drawbacks are of course - they use power and are quite noisy so not always useable at home.
Drill
A simple drill can reduce the time spend on winding the coils tenfold. It requires more setup than winding by hand, as you must be able to secure the mandrel while using the drill and also to hold the wire onto the mandrel while winding. This can be achieved in many ways - again - improvise.
Drawbacks
Drills consume power and are a bit noisy, so you can't do it all the time and you can't do it everywhere.
Angle grinder.
Angle grinders can be used to speed up the cutting of the rings by using very thin cutting discs. Again it requires more set up than cutting by hand as you will have to devise a way to "feed" the coils to the grinder disc so that it cuts the rings out.
Drawbacks
Angle grinders are noisy just as drills and apart from electricity they also need new discs often which makes them an expensive alternative. Unlike drills, you must also follow safety precautions - wearing goggles and gloves, etc to avoid eye injury or losing a finger or two.
This is all well and good, but you need something to make the rings out of.
http://drunkethic.blogspot.com/2011/03/on-art-of-chainmaille-part-3-materiel.html
