I had access to all the things I needed - squirrels, tools, wood, web server, ... I looked around the web for design ideas, then set up the following.
And, it only took me two years to get around to publishing this entry. Hope you like it.
Step 1: Design
I went with USB as it was cheap, simple, and quick. The biggest limitation is range. USB-2 has a range of 5 meters. I consider this build a "proof of concept". See future improvements section for alternate camera ideas. You can overcome the 5 meter USB limit with active USB cables or addition of a hub. ( or go with a non usb camera - a wifi enabled camera would be ideal )
Actual house dimensions are pretty flexible as well. My target for the house area was roughly 1'x1' and 18" tall. I used 11.5" pine shelving, and only cut pieces to length.
Tools used - I used all my power and air tools - table saw, nail gun, etc - but this build could easily be done with a hand saw, glue, screws, a drill, and a screwdriver.
Materials - wood $20, lexan $5, camera $15, software $30, screws and stuff were whatever I had around.
see additional information is in image notes in yellow boxes on the pictures.