Getting this from the entire thread and not just your first post. Hope I cover all your concerns.
Regarding the length of the cage, consider making the length just shorter than the height of a doorway. That way you know you can move it no matter where you live or what room you keep the cage in. On several occasions I've consulted people on building large cages who never considered whether or not they can get it into their house much less into the room they want it.
I now make sure to point this out, just in case it's relevant.
Regarding the thickness of the acrylic, I strongly recommend 1/4" for several reasons I won't get into. I agree that 1/8" could work, but I'd still avoid it. I say this especially not knowing the characteristics of Acrylite vs. other types of acrylic.
Also, absolutely build a 1/4" frame onto the face of the cage that the acrylic door will rest in. I'll post a picture that will hopefully show this.
Make sure to set the 1/4" frame away from the face frame at least an inch.
This frame will also allow you to use non-offset hinges, meaning you can then use piano hinges or flush hinges.
I recommend acrylic flush hinges. I also recommend solvent-welding them to the acrylic vs. screws and bolts.
Once again, there are several reasons why I recommend this. Once of them is that it allows to to set the 1/4" frame a ways away from the opening of the face frame. If you have screws poking through the other side they'd hit the face frame, causing more problems.
