This case has a hole for a light pipe to bring the on-board LED out of the case. The light pipe hole is designed for P/N 492-1154-ND from Digi-Key, a PLP2-500 12.7mm light pipe.
The case also has holes for four buttons to provide access to the on-board switches.
The Plasma snaps onto the posts in the base. It may be a tight fit initially, but the board stays in place. The base then fits into the top.
That looks great - love the light pipe! I’ve installed a Plasma 2040 on the back of my bike for some festive lighting and could do with something to stop it from rattling around :)