To get the nice 'glowing' effect with the LED box, we need to have a 'frosted' look on the box and need LED's that are diffused.
I only could get my hands on water clear acrylic sheets and water clear LED's. For all those who have the same, continue with this step.
If you already have frosted acrylic (opal acrylic) and diffused LED's, then you can continue with step 4.
1. Get the fine sandpaper (400) and place it on a table, with the sanding side up. Get a plate and rub it over the sandpaper in a circular motion. If one side is frosted enough, turn the plate over and do the same with that side.
Now you'll have a nice frosted looking effect we need (photo 1 and 2 to see the difference).
2. Do the same with the LED's. Sand the LED's until they get the nice diffused look (Photo 3,4 and 5).
Photo 5 shows you 1 diffused and 1 water clear LED hooked on a 3v button cell.