What can i use to contain a magnetic field. ?
I used to work with these magnets. Things won't fly at you at high speeds, but you have to worry about credit cards, just keep them away. 12, 1 ft is sufficient. Also, magnetic fields won't harm computers, but they will destroy disk drives. It should come in a wooden box that will keep the magnet far enough away from other metal to cause harm (or stick to). There are ways that you can contain the field (note the London effect and super conductors), but this is really not practical. Just use a little common sense and keep it away from things until you want to use it. And be careful because these can and do move unexpectedly (and very fast) and can cause damage.
Use a thick gauge cast iron box (it has to be a material with a high permeability) with a thick lining of something non magnetic like plastic, (I'm thinking expanded polystyrene here), because otherwise your magnet would just stick to the side of the box and you'd never get it out. One of those nice cast iron Le-cruset casserole dishes would probably work quite well provided you keep the lid on. Best of luck
