I have an interest in aircraft that flew in Palestine during WWI. The Germans
fitted a second radiator to their Albatros D.IIIs and D.Vs to help the engine cope with the high temperatures in this region.
The Ottman Air Service also used these twin radiator planes. Mainly D.IIs and D.IIIs.
So to model an Albatros correctly for this region you have to make a second radiator.
I took the option of making a resin casting of the original Eduard 1/48th scale D.III radiator.
 I also have moulds for the Eduard 1/72nd D.V, Roden 1/72nd D.II & D.III.

Using plasticine to build a wall around the thing you want to cast. I made the wall
about 1/4 inch high.

I found an article at the Missing Linx site about using Bathroom Silicone for the
mould instead of the normal RTV. There is no mixing with the Bathroom stuff. RTV needs to be mixed correctly or it wont set.

For doing single sided casting such as the radiator I think this Bathroom stuff is fine.

But would use RTV for more complex one part moulds.

The Bathroom stuff has been squeezed into the area we want to make a mould from.
Now we wait 24 hours for it to cure.

I used Easycast 2 part resin. This was purchased from Barnes Products here in Sydney.
I use 2 separate medicine cups for each part and then mix it in a separate cup.

In the case of the radiators I painted the mixed resin onto the mould. That way I can
control how much resin I need. In the case of the radiators its got to be very thing.
As you will see below.

The resin sets very quickly. Then very carefully peel the casting from the mould.
You can see how thin it is in the photo here. There was flash around the casting which
has been trimmed off with a very sharp knife and a steel straight edge. Just don't press
too hard on the casting with the straight edge. It is very easy to damage the thin casting.

Finished radiator casting in place. Of course I repeated the whole procedure for the
underside radiator.

In the case of the Albatros wing the raised rib detail had to be removed to match the
one on the right.