Hi! Here is my vision on how mini itx case should look like. This one made for motherboard with external power supply but can be modified to fit FSX.
This case does't allow you to place a graphics card inside.
For back light i used addressed RGB LEDs controlled by arduino. Model contains special slot for rgb strip WS2812. In my setup, strip reacts to hdd activity.
Mostly all components are hold together with thick FAN screws, exept top ring and lid. Ring holds on long fan screws and lid hold on standard plastic screws.
Top and bottom lids are sanded, primed and covered with paint. Bottom received additional layer of liquid rubber.
For body i used basic cloth (just find the one you like at local store)