Looking for some ideas on downdraught extract on my new table.

Its a 4x4 / 1250x1250 size table, so 4 x bigger than my existing one. Currently i have an extract system i cobbled together that does work pretty well providing i keep the unused parts covered to maintain airflow. It is a cross-draught really, air in at back and out at front, it has a water tray too but i don't use that anymore as its not as effective as extract.

So, on the new build, I can't simply bung in a big-ass blower as i have limited power spare and its only a small shop (double garage).

I am looking for smart ideas that could work, maybe some type of zoning system??

This is the type of fan i have...
http://www.ebay.co.uk/itm/3216990295...%3AMEBIDX%3AIT

I have ducted the outlet to outside, pipe is 4" and i know i can improve a bit on what i have by fitting rigid duct instead of the poor flex-foil stuff i have now.

Any suggestions here?

I have not built the bed yet so anything is possible.

Thanks