I have a 5.5g AGA and I'm looking to make a lid that will prevent carpet surfing, and still allow my HOB ac70 to fit. at first I was thinking how easy it would be to make a rectangle slightly smaller than the trim and then simply attach netting to it and then place it on the inside rim of the tank, but unfortunately that won't allow my filter to still be in place. I also don't want to get glass cut again because it's so darned expensive here.

Free cookies and cupcakes pellets and flake food for the best idea!

it's not too hard to cut glass yourself, especially if it is thin. For the filter, you can cut out a either a rectangular notch or make a single arc shaped cut. For the notch you could grind a small hole in the glass with a carbide bit designed for ceramic tile ($5 to %10?) at the corner(s) of the rectangular notch, and then use your glass cutter to cut straight lines from the hole to the edge (or from one hole to the other). For an arc, get a bowl or dinner plate the right diameter and use it as a guide, tracing it with your glass cutter. Then use the steel ball on the end of your glass cutter to cause the glass to crack along your cut. (use 1/8" or 3/16" glass to make it easy)

You can often find pieces of glass or cracked aquariums for free, or cheap (craigslist?). The dumpster behind a glass or window shop is a good place to look (after hours). They usuallyl break glass when they throw it away, to discourage this sort of thing, but you should be able to find a broken piece that is larger than you need for a nano. Avoid tempered glass, which breaks into a thousand little pieces when you try to cut it. To make the sharp edges safe after you cut, just rub the sharp edge of one cut piece against the cut edge of another (with the two pieces of glass oriented in different planes, about 45 degrees apart). Wear eye protection, and sweep up all the little micro slivers of glass when your done, but it works to dull the edge.

If you don't want to work with glass, use acrylic. It's easy to cut with a jig saw (with a fine toothed blade). Just stop often and cool the blade, and the acrylic, so that the friction wont make it melt. If you cut it with a table saw, use a find toothed blade, and have someone cool the blade with a spray bottle as you go. Flat acrylic will bow over time because of hot lights and gravity, but not if you glue 1/2" or 3/4" strips of acrylic, edge on, onto the underside of the lid. Glue four strips, close to the edge.

Realize that a lid will decrease the amount of light that gets into your tank, decrease gas exchange at the surface, and decrease evaporation, and evaporative cooling, so your tank might run a degree or two hotter.

Are you are wanting to make a cover, or could you just make the edge of the tank taller? It would hide all the things hanging off the tank if it was made out of a smoke colored plastic. It could stay open on the top.

Buy window screen frame, and some nice mesh that allows the most light to get through. Get a splining tool and spline the mesh in

You would just need to be creative with the placement I guess.

Eggcrate works pretty well also.