text: There are no permanently magnetic materials - not even "permanent" magnets. The best you can achieve is something that holds the same relative magnetic charge over a range of temperature. This is because all magnets are affected by other magnets (and their fields).\n\nTo magnetize a ferrous material (I"m assuming here that your sheet of material isn't stainless), there's two basic methods.\n\nThe first is to use a known magnetic field (i.e. an existing magnet). In this case, run the magnet from one end of the sheet to the other in even motions. Always go in the same direction, and be sure to cover every possible inch of surface area ... on ONE side of the sheet. The passes also have to be made in the direction of the sheet 'grain' - which means along the path that the molecules of steel tend to line up naturally along.\n\nThe second is to employ electricity. In this case, form the sheet into a tube (either a single layer tube, or an insulated sprial as noted previously). Be sure to insulate the outer surface with a very thin layer of something - like paper. Over the insulation, wrap several turns of wire (insulated or uninsulated - it doesn't matter except that the insulated wire usually takes up more physical space and will carry more current). The wire needs to be applied evenly from one end to the other, always going the same way around the tube of steel. The higher the number of turns, the stronger your magnet will become - therefore you could use multiple layers of wire (either with a connecting single turn to return you to the original starting point, or by making another parallel path. Finally, connect the ends of the wire to a DC voltage source, and allow current to pass through the wire. \n\nYou now have a magnet of (some) strength that will remain a magnet even after you've removed the wire and unrolled the sheet. Remember - other magnetic fields will affect it, so it MAY eventually become demagnetized (or at least have its field strength reduced to the point where it is no longer usable for your purposes).