I can't advise yuo on brands, since European brands are generally not for sale in the US and the other way around. Try the yellow pages and look for a chemists shop. Anything with "resin", "silicones" or "mold making" can help you. Go there and ask advice. Some sell their products on the web. Search this "scratchbuilding" forum for previous posts. the issue has been discussed.
For molding techniques, I refer to the "xeroxing Ammo Boxes" article in the "/features" on this site, or try this fabulous Japanese
Molding techniques website. Mr Mori explains all the tricks of the trade in Japanese, but the pictures are quite clear.
Good luck !
Jan