This is an amazing induction heater and now you can build your own for fun or as a powerful tool. I have put together an extensive tutorial at http://inductionheatertutorial.com with schematics for building a 3 and 12kw unit. You'll be able to instantly melt steel aluminum and copper. You can use this for brazing, melting and forging metals. You can use this for casting, too. The tutorial covers theory, components and assembly of some of critical components. The tutorial is large. I will go over the main steps here to give you an idea of what goes into a project like this and how to design it so you don't blow any mosfets or IGBTs.
If you wish, you can refer to the link above. This Instructable presumes you have a good understanding of electronics and induction heaters. Let's begin.
As an aside, I have put together a very accurate low-cost cryogenic digital thermometer. Watch me put it up against a standard name-brand using liquid nitrogen for the test.