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This frame will serve as the bottom of the cage. Make sure you lay it down in an area where you have sufficient room to work, but it doesn’t have to be where the cage will remain permanently.  Once finished, the frame will be small enough to move with a friend. If you are building the cage indoors, make sure there’s enough room around the frame for you to easily move around to each of its four corners as you work. The 2 ft (0.61 m) pieces of wood are posts that will hold up the second frame as the top of the cage. Place the 2 ft (0.61 m) piece upright inside the four corners of the frame that’s on the ground, then use two 3 in (7.6 cm) wood screws on each post to secure them to the frame.  Align the posts so that they are standing perfectly upright before screwing them into place. Mount all four posts to the bottom frame before moving on to the next step. Ask a friend to help you lift the second wooden frame up so you can slide it over the upright posts attached to the bottom frame. Position the upper frame so the posts are inside all 4 corners and lower the frame until the posts and the top of the frame are flush or even. Once you have the frame positioned, you and your friend will have to hold it in place until it is secured. Have your friend insert a 3 in (7.6 cm) wood screw through the upper frame and into each upright post to hold it in place. Once those first 4 screws are in, you and your other friend can let go of the frame. Then add an additional 3 in (7.6 cm) screw to each corner to ensure it’s secure and stable.  You may be able to use just 1 screw per corner, but 2 will be sturdier. With the screws in place, the basic frame of the cage is complete. A rabbit cage should include an area that’s elevated from the ground and offers the rabbits shelter. Lay a piece of plywood that measures 3 feet (0.91 m) by 2 feet (0.61 m) across the bottom frame on one side. Then use wood screws to secure it into place.  This step will create a small portion of the cage with an elevated floor. The remainder of the cage floor will be open to the ground. You can purchase pre-made rabbit shelters from your local pet store, but there are a number of inexpensive alternatives. Any overturned plastic container with a hole cut for a door can serve as a rabbit shelter for inside your cage.  The shelter will give the rabbits a place to hide from rain or intense sunlight. It is easier to put the shelter in place before enclosing the cage, but you’ll still be able to access it from the bottom when the cage is complete.

Summary:
Lay one rectangle flat on the ground. Screw the remaining 2 ft (0.61 m) pieces of wood upright into all four corners of the rectangle. Lower the other wooden frame onto the upright pieces of wood. Have a friend screw the second frame into the top of the upright posts. Lay the plywood down onto the lower frame and secure it with screws. Place a rabbit shelter on the plywood.