Thank you Senile...I think that my fans work pretty well. I have two "green house style" fans in each corner of the booth. I made my own exhaust stack, and used chicken wire to hold the fiberglass exhaust filters, seems to work fine. There are louvers on the outside of the fan, so it keeps the weather and pests out. I find that I need to feed my booth lots of air, otherwise it chokes out the air movement. In the summer, I leave the shop door open to allow lots of fresh-air to enter into the intake filters. Pulling air from just inside the shop seems to reduce the airflow, so bringing in outside air does assist in the air movement.