The use of metal pipe is common in intercooler systems, exhaust sections, and a number of other applications, which gives you different options from which to choose. Diameter can vary from 10mm to 100mm and length can vary considerably as well. You can find metal pipe with elbow bends from 45 degrees to very near 180 degrees.
Two commonly used materials include steel and aluminium alloy. Remember to carefully opt between DIY and professional installation.