this turned out SOO COOL!
Very easy if you have some basic power tools. I started with back piece SNAPPED to the size of my tank, a 20l.
I just REALLY scored the sheet for length and width and snapped it.
The narrow strips I did not want to snap so I cut them on a bandsaw. The reason you need the strips is to make two bows. The bows get the LED strips back from the main sheet do it diffuses nicely.
I glued a stack of two short strips along the edge so the bows had something to catch on. Next glued the bows in and then glued a couple reenforcing pieces over the ends of the bows.
Plugged it in....Spectacular...what really caught me by surprise was how nice it look even with the light on! I was planning on using it as a mood light after the main light is out. But just might keep it on with the main light!