There's a lot of surplus equipment out there that can be used as the basis for a homebrew project. Here's a way to make it look more professional.
For example, let's take this...
...and make it look like this:
It's actually very easy. Here are the steps I follow.
First, For the panel, I measure its dimensions and the locations of all holes I want to use. Then, using an electronic drawing program (I use Adobe Illustrator, but others I know use Autocad), I accurately place all hole locations as well as any labels I want to add on my panel drawing.
I then print out the panel drawing. If the panel is larger than, say, 8.5 x 11 inches, you'll need to create a "B" size sheet (11" x 17"). My printer does not print B-size sheets, so I instead print two "A" size sheets, trim their edges, align them (note the alignment marks in the overlap area), and then tape them together so that they form a larger sheet. If you don't have a light-table for accurately aligning them, a window works fine...
I then go to the local copier store (here it's the "Kinko's" chain) where I copy my "composite" drawing onto a B-size sheet (so that it's a single piece of paper, not two taped together).
I then laminate it (the local Kinko's has a laminator).
And I cut out the panel overlay (and any large holes) with an Xacto knife...
Finally, I glue my overlay to the original metal panel using "Adhesive 77" spray adhesive (manufactured by 3M) and cut out the remaining holes, using the holes in the original panel to guide my Xacto knife.