Print tiles!

... Paint?

If you want it futuristic, replace the hardboard panels with the cheapest clear plastic you can get, which is... a clear plastic mat for an office chair. It'll be clear, with a pebble like texture. I used it on an enclosure I made and it came out great. One mat had enough area to do all the sides, and you can still see through enough to notice if something is horribly wrong.

Or, paint it and then stencil on some angled lines or something in a contrasting primary color. Maybe a different color for each side.

I would be thinking along the lines of #Steampunk. Rivets, fake leather, copper paint, exposed gears, guages, rope, etc.