I want to build a vacuum hold down for router to cut light material like pvc, coroplast etc, about 1/4", any idea what is the best way to do something like this?
Thanks.

you could use Vacuum Pucks, for hold downs, best thing is they are adjustable location wise on your cutting bed.

where is the good place to get it? how big the vacuum pump can do the trick?

here is a sample. should be pretty easy to construct or get there.

http://www.iedu.com/DeSoto/assembly.html

joe