Most of these models have been constructed from kits - etched brass, white-metal or plastic. I find building these kits very rewarding, and would encourage anyone who has not tried it to have a go! White metal kits are generally thought to be easier and quicker - though they often require a lot of fettling and added detail. Brass kits are not as hard as they look, though are generally more expensive. I have given details of the manufacturer  in the caption accompanying the models, and. you can find details of those with web-sites or e-mail on the Links Line, or support your local model shop and see what they have available. Useful hints about building models are included on My Line