The ordinary track range from Carrera might not cover your needs or you might want to have a more realistic section than the ordinary range offers. To cut/create single lane parts could pretty easily be done by yourself, see the DIY – Track parts section and there are several guides/tutorials on Youtube. When it comes to more advanced trackparts/-sections, I have been using Burkhard at Homegrandprix.de, in Germany. He is simply outstanding. Here is a painted example of his customized hairpin. Contact him if you need a specific customized track section. Pitslot.de is another company that customizes sections.