I'm adding this link so I can find it later. This is a trick Robert uses to secure wiring and I really like the idea. I'm going to give it a try. They use earth magnets and bond zip tie retainers to them and use these to secure wiring harnesses without having to drill or weld to the sheet metal.
www.appliedmagnets.com
We use either the CUP-26, which is a 49 lb pull, or CUP-20, which is 26 lb pull. Much better pricing over McMaster on magnets.