First step: research the options. I'm thinking of building a container to concentrate the suction power on one side of the cage. Hook up the outlet to a baffle box with filters and a cyclone chamber (or two...) on the inlet.
Building a shopvac system from scratch
Thanks for your input! Interesting point re. pressure vs. vacuum. The friend who gave it to me insists that it sucks really well but a short test run seems to confirm your statement. A strong airflow at the outlet and barely noticeable flowing in. I'm hoping that containing it in a box will create more suction but I am totally inexperienced in this. If all else fails, I'll just sell the fan and buy a ShopVac :)