I didn't get it if you are after the result shown in the picture, or a "neon" with acrylic case, so here are two examples. Each of them is using a different approach!
acrylic - the one with sunlight - using SSS materials for all objects
acrylic-lit - the one with neon - only two objects have materials updated, this time using translucency only, the background square and the "corona" text. Square has a light inside - I think it looks pretty ok, "corona" has the material of the back face set to CoronaLight and normals flipped so that it's glowing inside only.