Looking for a particular style of chassis

I’m building a tube amp and would like to use a case similar to the Eddie Current amps. The “body” is a U shape with a rear panel, and the top and bottom are flat, overhanging pieces of aluminum. Any help finding the “body” would be appreciated as the top and bottom are easy to procure.

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The channel bars could be cut to length, mitered and then joined at the corners to form the body. Another idea would be to cut an off the shelf chassis. Like the basic Hammond models. One side already has a removable panel. Cut your opening on the other side, leaving enough material around the edges for the cover plate to mount to.