Measure the dimensions of the tank for which you are going to make the lid. Use a tape measure for this purpose. Dimensions of the tank will help you determine the quantity of materials you will need for this project.
Referring to the dimensions you took in the previous step, purchase a roll of screen of appropriate length and width along with a piece of wood that will best serve the purpose.
Carefully unroll wire cloth and place it over the top of the tank. Someone else might have to hold it down at one end because of its stiffness.
With a pair of wire cutters, trim the wire cloth to a desired depth. Make sure there is enough room on all sides of the wire cloth to accommodate the piece of wood that you bought earlier. A piece of wire cloth approximately 1/3 times longer on all side than necessary would work perfectly.
Carefully cut the wire cloth according to the inside edges of the terrarium. Bend down all four sides and fold those flaps in. When you are done, carefully fold the excess wire cloth upwards on all four sides and over the flaps that you created earlier.
Take off the screen from the terrarium and move it outside with extreme caution. Set aside the screen because you will now have to do some woodwork. Refer to the dimensions of the terrarium for which you are making the lid to cut an appropriately sized piece of wood. Be sure to cut the wooden piece 1 inch longer than required.
Use a staple gun or upholstery tacks to secure the screen to the wood. You can also drive in a few nails if required and your lid will be complete.