Not quite true, Questor.

The parts are copyright, meaning that Deagostini own the right to copy them. Making copies for sale or for yourself, would still be illegal.

however, I understand what you are doing. you are making your own parts, to your own designs, to fit in their model as replacement parts.

It is classed as "Fan Activity" and there is a certain leeway normally granted in these cases. I mean, it would be rather low for a company to complain that to make the model you want, you are being forced to buy their £800+ kit.

Unfortunately, I am also not good enough to be able to give you the information you need due to the part being a hemisphere.

For example, take a sphere such as the Earth. start at the North pole, and travel directly South. Turn 90° left when you reach the equator, and travel along the equator for a 1/4 of its distance. Make another 90° left turn, and travel North the same distance you travelled South.

If you try and draw that on a flat piece of paper, you have walked un a 'U' shape, but on the globe, you've actually walked a triangle with three sides and three equal 90° angles.