I wanted a small panel to be able to install two switches under the dash fascia without drilling more holes in our old red car that has many extra holes already courtesy of former owners. I drew up a bracket to be made from sheet aluminum, formed, painted camera case (a.k.a. crinkle or wrinkle) black, and fixed in place by two worm gear type stainless steel band clamps. See below.
Not having the sheet metal working equipment Nick Acton fabricated it for me from my drawings of the flat blank and formed part.
Works for me, and I like it. The basic design could go full width between the scuttle hoop supports.