While living at an apartment with no sliding glass door for putting a pet door insert in, I made this for my cat to go outside through a patio window. Using a piece of plywood and some printed parts, I was able to make a functional pet door my cat loved! I designed it split to fit on my printer, with the front and back of the frame the same. Two sets of the frame is used to sandwich the plywood. 2013 EDIT: For the original application, I was using two 1/4 in plywood sheets, so the pet door frame is good for 1/2 in of material. I've recently uploaded a zip file including the SW parts and assembly, as well as a STEP of the door for user modification as desired.