You want a custom metal base plate to mount joystick and buttons. Not a plexi overlay panel. Correct?
If you want plexi overlays, either Art’s Hobbies or Focus Attack has what you need. Else, nowhere I’ve seen can help you with a metal base plate replacement for the HRAP4.
There’s been a couple of people in the past that have offered custom metal replacement CPs for sticks (blklighting21 and B-Boy Tekken), the former has been MIA for a few years, and the latter has stopped offering the service.
As far as I know, only @“Jasen Hicks” offers metal replacement CPs these days.
If you want something right now (may not be practical with Jasen due to his deployment), you’d probably have more luck getting a custom panel designed and cut out on your own, unfortunately.
Lots of plastic under the panel that limits options… having taken them apart and made a replacement 6 button, the Vewlix layout is about the only one that “works” without cutting a bunch of plastic support away from under it.
Yeah, the top row of buttons of the Vewlix layout are essentially butted up against the plastic casing. You really only have one spot to keep the lever in that case for the same reason, so keeping the layout true to form is likely not possible.
Based on your desires, I would suggest a Panzer Fight Stick… but that’s just me.