Step 1: All the Different Stuff You Gonna Need
fannypack for putting tools into,
more card board "cereal box grade",
12v fan from computer power source "free from computer shops",
sticky stuff made for your cupboards,
Step 2: Top and Bottom
When designing the outline for the ventilation ducts be sure not to cut too much as it will make the top of tray flimsy and weak.
Make sure that the duct where the fan will sit is wide enough for the fan.
Trace the design onto the bottom piece of the tray.
Step 3: Tray Walls
Cut with the grain of the cardboard to help you keep all pieces the same width.
Tape a whole bunch till all pieces feel stable. Tape along the outside seem to make it air tight. You could also seal the inside walls to increase a more even airflow.
Step 4: USB Fan
Cut USB cable to desired length and strip casing
You only need the red and black wires from the USB cable so don't worry about the other two you don't need them, just make sure they aren't exposed.
Splice the red to red wires and the black to black wires of the USB to the fan. you dont need to solder them, you can twist them together and cover them with tape.
Cover the splices individually so red and black never touch then wrap the wires to make it look nice.
Step 5: Fan Case
cut part of the side of the back wall out to allow the case to insert into the tray.
place the open side of the down on the tray to adjust before taping.
tape the case to width of the duct but not to the tray yet.
cut the sides of the case to channel air down into the tray. be sure to place the fan far enough back so the screen is able to lean back.
fold the top of the case down and seal it with tape to the side.
*Be creative there's a lot of adjustments you will need to do with the case. you could even get two or three fans on although you will need a larger power source since USB has only a 12v power
Step 6: Like the Last Step of This Instructable!
Cut anything off that obstructs the top from siting flat and ad cardboard or tape anywhere there are gaps between the top, sides and bottom
Tape the top down and seal it up.
Cut the gooey stuff to size and tape it down.
Make sure you seal the edges of the top since cardboard is slotted.