Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

They don't know what you "need", so there is no way they could "tell" you that, but they offer a selection of materials from which you can decide what you need, however, the decision is yours to make based on what is available.

There is nothing in the catalog (it appears that they don't offer it in hard copy anymore) that isn't in their website catalog, so that resource should be adequate.

Perhaps I should also point out that your local hardware store likely has small copper tubing and fittings for hooking up things like swamp coolers and the like, so perhaps a trip there would be of service to you.