[Nitram Draw]

The only way to get one is to have your computer ship design minister design it for you. If you try to design one yourself you get a warning "only one component allowed" or something like that when you try to add the second yard component. Apparently the AI design minister is able to inore this warning. Once you have it as a design you can build as many as you want.
The easiest way to get the design is to copy it from the AI's vehicle design file and paste it into your races vehicle design file then turn on the design minister for a turn or two until he decides to design it for you.