Place the cardboard box inside the environmental cabinet. Position it with the top facing upward.
Cut out a piece of cotton cloth or another fabric. The fabric needs to be long enough to cover the box's open top. Place the cloth over the box top and attach it to the box with glue.
Place the drawing on top of the cloth. Make sure the fungi are facing up toward the cabinet's top.
Set the humidity to "Minimum." Set the temperature to 35 degrees Celsius (95 degrees Fahrenheit), according to Conservation-Issues.com.
Allow the fungi drawing to dry out, or preserve, for three days. Turn off the cabinet and remove the drawing.