This is an idea that I have been toying with, but as my 5 gallon is a bow front it may be a little harder to cut. Anyways, the idea was to make something similar to the Perfecto glass hoods. Cut two pieces of Plexiglas so that when they fit together they are a little smaller than the tank. Buy the replacement hinge and back cover for the perfecto glass hoods (they are not too expensive, around $3.00 each and they can be cut so order a little larger than you think you might need and cut to size). Use one of those stick on hooks for the handle. Voilà you have a cover. As for lights you can do one of 2 things, you can splurge here and buy a light strip, or what I did for my 55 gallon that has a glass hood I purchased two inexpensive fluorescent light fixtures (around $10 each) and went to the home improvement centre and purchased some inexpensive ply wood and made a simple box/cube leaving the bottom and top of the cube open, took another piece of wood and used hinges to attach the wood to the top of the box and affixed the lights from walmart in the box. Now you can use screws to attach it to the wood, but I used simple outdoor mounting tape, worked just as well and didn't have to worry about lining the screws up properly. I then painted the entire box black so it matched the aquarium trim. Oh I also lined the entire inside of the box (and the bottom of the lid) with aluminium foil to act as a reflector. It worked really really well and the entire project cost me around $30 as opposed to around $200 for aquarium light strips to fit a 55 gallon tank. A 5 gallon tank would be much less expensive. If you have live plants, you can purchase either a grow fluorescent light (also at walmart) or if you can find it, just buy the fluorescent replacement tubes for the grow light and replace the original bulb that came with you light. Now I don't have live plants so I didn't worry about it. I just got 2 18 inch fluorescent undercabnet lights and it lights the tank really well.
If you are thinking of doing this pm me and I can give you the links to purchase the replacement hinge and back strip you will need for your plexi top and I can send you pictures of the lighting box I made.
