I currently work on an interesting project: A customer ordered an Atari 7800 in a hifi rack housing.
We finally agreed to include an AV+, Stereo/Surround and Pause mod (for Atari 2600 mode).
A background light in blue which can be switched off completes the design. Power supply is internally and a SCART plug including the joystick ports on the back. Pre-fitted with PSX joystick mod.
I started with a mockup how it would looks like after completion:

Picture: front view

Picture: back view
This thread will describe the progress of this project.
I first started with opening the chassis, try to find the right location for the mainboard. The mainboard requires some changes:
1. power regulator must be moved to housing (better cooling and reduction of height)
2. capacitor must be rotated else the chassis can't be closed
3. cartridge slot must be turned by 90 degree angle to the front
considerations:
1. reduce the length of critical signal pathes by moving the mainboard to the right position.
2. power supply will be added without modification which could be critical due to regulations and insurance
3. the chassis must be modified without adding cracks or scratches (the black painting is quite sensible)
4. the keys must be identical to the already builtin ones
A visit at my local dealer provided the right material. I finally choose silver function keys which are altered by painting to the right color match.
Metal stripes are used to create the function key and connector panel out of it. It is then colored in black with several levels of painting. The pictures below illustrate how the front was created. If you have the right tools all visions comes true 