A main door to access the coop and a small chicken door are the only doors really needed. But I added cabinet doors, a nest box door, chicken door and a main door on this thing. Hinges were from old bath and kitchen cabinets.
The main door is made with old porch flooring. Boards were attached diagonally to the siding cutout with nails; then I used the jigsaw to clean it up around the outside. This made a more old fashioned looking door. The nails will stick out the back side, bend them over or cut them and grind the stubs smooth.
The other doors were made directly from the siding material and some trim wood. I just attached hinges and handles with some trim around the edges. The trim is important to close the gap from where the saw cut the siding. I added some plastic near the top to shed rain over the cabinet doors.