Mold making ~ silicone/resin

I need to make some duplicates of some Corbels I have. Rather intricate and detailed, the size is 20" high, 8" wide and a 9" profile . I watched "How it's made" the other night and it was the exact material I am looking to use in creating duplicates of these ~ in rosin.
Does anyone know where to get these materials ~ the silicone rubber liquid and the resin composite to make the object itself. Better yet, has anyone created duplicates in this way, or if you have another idea ~ i would be grateful if you would share you're opinion. below is the corbel itself ~ I have 12 of these I have to make they are being used as a window treatment on the exterior with a roman style capitol /entablature ~ on the top
thank you~ :)
Brian

These guys are the best out there.

http://www.smooth-on.com/default.htm

More:

http://www.traditional-building.com/3-moldm.htm
http://www.jgreer.com/

thanks so much for the information~ this company is great!
thanks again,:)
Brian