Measure the length and width of your amp.
Purchase or acquire cardboard boxes that are at least 5 inches longer, wider and deeper on each side than your amp measurements. This will allow you to space to layer materials on the inner surfaces of the cardboard box to insulate the sound.
Measure and cut five pieces of Styrofoam the same length and width as your amp measurements.
Apply a layer of craft glue to one side of the first piece of Styrofoam. Press the Styrofoam onto one inner surface of the cardboard box and hold firmly for 30 seconds. Repeat this step for each remaining surface inside the box including the bottom of the box.
Measure and cut five pieces of your soundproof material such as Dynamat with the same length and width as your amp measurements.
Apply a layer of craft glue to one side of the first piece of soundproof material. Press the fabric onto one inner surface of the cardboard box and hold firmly for 30 seconds. Repeat this step for each remaining surface inside the box, including the bottom of the box.
Cut the lid off the egg cartons with your scissors. Apply a layer of craft glue to the bottom of the first egg carton. Press the egg carton onto the bottom corner of one inner surface of the cardboard box. Glue the second egg carton next to the first to create a row of egg cartons on the surface of the box. Continue to create tight rows of egg cartons until the whole of the first surface is covered. Repeat this step for each remaining surface inside the box, including the bottom of the box.
Place the amp inside the soundproof box. Cover the top of the box with a large cushion. This insulates the sound further without restricting your access to the amp too much.