Fake fireplaces add a touch of realism to stage sets, provide cozy detail for children's playhouses or simply act as a space for "camping out" in the living room. You could get complicated with wood and screws, but the simplest fake fireplaces are made from cardboard. This doesn't mean they have to look childish. All it means is the fireplace shouldn't be exposed to any real fire or heat.
Unfold the flaps of your 5-foot box and place it upside down on the floor. Place the bottom of your 3-foot box against the bottom of the larger box. The edges of the boxes closest to you should be lined up exactly, with the 3-foot box centered on the edge of the 5-foot box. Trace around the 3-foot box with chalk.
Poke the tip of your utility knife into your chalk line and cut out the outline of the 3-foot box. Spray paint the outside of your larger box a cream color and the inside of the smaller box black. Stand the larger box on its side so your 3-foot hole is on the bottom center of the front of the box. Stand your smaller box on its side so you can see into it easily. Cut off the bottom flap of the smaller box.
Pour a little red acrylic paint onto a paper plate. Dip a rectangular sponge gently into the paint, blot it on a clean part of the plate and press it against your larger box. Line the long edge of the sponge up with the edge of the 3-foot hole. Lift the sponge straight up and press it down right next to your first rectangle. Continue, creating bricks this way all over your box. Let the paint dry overnight.
Slide the smaller box into the larger box from behind. Line the opening of the smaller box up with the hole in the larger box. Glue the flaps of the smaller box to the inside of the larger box around the hole. Let the glue dry overnight and enjoy your new fireplace.