I have done the 3d Backgrounds before. I used 'Aqua one' brand of 3d background tiles 50inch x 20inch. These can be pre cut and siliconed into the tank if necessary. I was luck enough to have a lip of glass on the top of my tanks, so i did not need to silicone them in. This made cleaning a bit easier, but still it was a major task.
After a while I removed them permanently, heres why:
The backgrounds gave something for the BBA to grow on.
I would occasionally find my kuhli loaches wedged in behind the background (alive)
My Echinodorus tenellus was sending runners behind the backgrounds, and there were dead spots behind it also where I had white slime patches developing.
After a while I had to decide weather I wanted a pretty tank with lot's of maintenance, or a basic tank with minimal fuss.
I put the 3d backgrounds behind the tanks on the outside of the glass (like a 2d background) and although the effect isn't as nice, It saves me an hour or two cleaning them every fortnight.
Look for the 'aqua one' brand online. I got mine at an oz pet shop
