I've done it, it's not easy, but it's a great way to make nice, light cages.
You shouldn't use pre-made window frame - it's too expensive. You have
to use the light aluminum frame they sell and do it yourself. It's 3/4" X 1/4"
I believe, and ~$3 per 8 foot section. The stuff Home Depot and Lowes
sells is designed for making screen window frames, and it fits into the
grooves on the outside of most new homes. It's a bit thinner and weaker
than the stuff I use, which is more square in cross section. It's used for
wooden frame windows, and is usually only available through aluminum
screen suppliers.
The home depot stuff will work, but it will be less rigid.
You have to cut the aluminum frame, insert the plastic corner pieces, and
make sure it's all square. Then you have to cut the aluminum screen,
brace the frame (to prevent it from being bent while you run the screen),
and lay the screen in the groove with a screening tool. Then you have to
press in some spline wit hthe screen tool. Then trim the screen. Repeat
for all the sides.
To join the pieces, you must measure and pre drill holes, and then use
sheet metal screws. Hinges can be a pain, as sheet metal screws wound
be able to hold the hinges in place. You either need to use pop rivets
(work well, are cheap, but permanent), or use machine screws with nuts.
I made a bunch to sell at a reptile show in May, but the show was poorly
advertised, it was horrible. I still have a bunch left.
The ones I made for the show are 2'x2'x3', all black frame and screen,
even on the bottom.
They're really nice, very strong and light. I always made my own cages,
and I tell you these are much better than using heavy wood frames. Even
the light cages I made recently out of 1x2's are heavy in comparison to
these aluminum cages.
If you only need one or two cages, you're better off buying them
premade. You need certain tools to do it (aluminum circ saw blade, drill,
screen tools, different bits, etc.), and it takes practice. Escpeciialy the
screen. It's a pain to do, and I screwed up about 20 feet of 3' wide
screen before I had it figured out. v If you're going to make several cages ,
it's a worthwhile skill to learn. Heck, I've even screened in our windows
since I've learned how to do it...