No. Magnetics within the chassis itself will be dependent on the circuit design and component placement primarily and component choice secondarily. Like you don't want to place your power transformer near your input connectors so you put the tranny on one corner and the inputs on an opposite corner and on the longer dimension of your shape, as far from each other as physically possible.
Options:
Consider finding a copper plate to use for the top and make a wooden box frame to mount that on.
Use aluminum. This has options for having it anodized in just about any color you might want.
