I needed a canopy for my new-used (got from craigslist) 75 gallon tank
. I learned much from building my own DIY stand
for it. I used Google's sketchup program for many hours to come up with what I was looking for. I had used the program to do the stand and even though it took many hours of design time, it really made putting it all together extremely easier than if i did it on the fly.
I wanted a canopy that was high enough that feeding the fish would be easy, as well as doing routine and simple maintenance without having to remove it. I did lots of research on Google, looked at lots of images and decided I wanted one where the front would lift. My carpentry skills are not really good enough to do cabinets doors and I thought they might limit access anyway. I figured I should err on the side of height. Once I add lighting, I may still have a couple of inches to get my arms in, remove or add rock and whatever else. So I decided to around 9" high.
Took me a while to figure out how I was going to do the lid so that I could easily feed the fish, reach the bottom of the tank and perform and maintenance on lights and such. I ended up designing the lid to be attached to the top, which would be three pieces and get hinged (using a piano hinge) so that the front and part of the top would lift out of the way, or fold back if you will. I went this route for two reasons - to make more room to access and I wouldn't need any sort of "prop" to hold the lid open. When I open it, it'll essentially fold over and rest on the other half of the top. I hinged two of top pieces together using a piano hinge. I know it'll rust over time, but they are not that expensive or hard to replace. The third part of the top you see in the drawing below will just be a 1 x 4 that rests on the back half so it can be lifted out in case I need to get access to the back of the tank.