This was on Googles "How to of the Day" today

[SIGNGUY]

This was on the Google "How To" of the day their Home Page. Pretty basic , but for us newbie painters, maybe it could work... I may try it in a few weeks?
http://www.wikihow.com/Create-a-Paint-Booth-in-Your-Garage

[Jim]

Well documented and looks nice, but you could run into a few problems...

I had attempted this type of setup some time ago and ran into a problem getting the over-spray out of the booth. The fan didn't move enough air and this allowed over-spray to settle back onto the fresh paint, not good!
Since spray guns use a lot of air, this air is released into the booth where it increases the booth air pressure. If the fan system cannot reduce this over pressure than the over-spray particals will eventually settle on the semi-drying paint and affect the finish.

[sodaworks]

The other problem I see is that a box fan isn't explosion proof. Paint fumes and electric spark could get nasty. Just be careful.

[sodaworks]

Here's mine. Not too expensive and works great. The good part about it is when it's not in use it's totally out of the way.