I don't know if you saw my post from a few days ago, but I am almost there:
two pieces of PVC that will screw together I used 4 Inch
Small Board as a base
Claulk (to seal PVC to Base)
Larger capacity Aquarium Pump, (I go one with 2 outputs
Aquarium Hose
Regulator valves (to tune airflow)
Some type of barrior materiail (I haven't worked this out yet, but Vaccume cleaner bags may be the key.)
thread your drill a hole or two in the lower PVC for your regulator valves to go in. Caulk your lower portion to the board. Tread your PVC Together with the barrior in between connect your pump with the hoses and you should be ready to go.