how to attach a roof rack?

[BGGB]

I have plans to build a roof rack this summer for my 88 but would like some info and pics if you can get them of how the rack attaches to the gutter on the roof. I've seen pictures of roof racks but not up close. as i understand it is a sortof clamp that holds it in place. also how many supports and clamps should i build for the length of the rack, i was thinking 4 but maybe you have different ideas. Thank you

[SafeAirOne]

There's a few different ideas on this thread: http://www.roversnorth.com/forums/showthread.php?t=5273