I replied to your post in the Main Forum, but this seemed like a better place to post my pics. Not trying to be a Project Announcement Within A Project Announcement, but I have a Power Drive upright which has a totally different top than your machine, but happens to share the lower profile and control panel mount. I'm on my third revision of this control panel, and I chose to use MDF with a plexi overlay sprayed from the back with Pactra R/C car body paint.
Here is the second panel along with the original base I used as a template... I'm too embarrassed to show anyone the first.

It was just plain gloss black, but I made a couple of sophomore effort mistakes like not hiding the metal trackball frame and the separate mouse buttons. The original panel had these crazy "shifter" sticks, which is why the base has the huge holes.

Here is the latest panel mounted to the cab. I painted it to try to follow the theme of the side art. I countersunk everything and integrated the mouse buttons as the bottom row of the player 1 controls.
You can see how it bolts right up to the original Bally base.

Just a closer shot that shows the Groovy Game Gear spinner and slightly offset t-molding to make the plexi flush with the base.

Flips open just like the original.

Fired up with the lit trackball. I've kept the original bezel, which really limits the monitor size I can use. It can fit maybe up to a 21" monitor, but right now the original 19" size is in there.

I did have to trim the inside of the metal base just a bit to make room for the trackball mounts. Overall, after basically learning how to make a control panel on this very machine, I think you're better off going this route instead of messing with the metal. The wood is quieter and feels more solid.