I use those (18"?) magnet bars which I get from HF unless I find them on sale, rarely. For me, I make a base attached to a 1/4" plywood backing and add the magnet bar. This is for my tools. I finally got tired of trying to find various allen wrenches, chuck keys, and tommy bars so I got a magnet bar just for them and other loose things such as my mini sorby chisels. Everything is on the wall opposite my lathe and quite handy. The only thing I have mounted to the lathe is a cut off paint brush with rare earth magnets. I use it to wipe my carbide tools on.
Stan