Here's a couple of shots of my red perspex screen.
As you can see I had the guys turn the sides in slightly so that there's no light leakage from the sides.
The top is turned over enough to hold the red screen in place and just slides over the top of the lappy.
One thing to remember when measuring up the screen is to allow enough space on the top fold for the LCD's locking latch.
Hope this helps.
