Have you guys seen this project from
Open Source Ecology?
They're offering from US$ 1k to 3k to the best induction furnace project submitted.
The project should include:
1. Design of an induction furnace circuit scalable up to 50 kW in units of 1 or 5 kW
2. Design allows for power and frequency selection
3. Power source may be either 1 or 3 phase electrical power.
4. Specifications of a cooling or heat dissipation system
5. Adaptable design specifications for primary coil windings
6. Geometrical design of melt chamber and basic power transfer calculations
7. Melt chamber includes provisions for loading and pouring.
8. Complete bill of materials
9. Fabrication files for circuit and other components
10. Sourcing information for components
11. System design and process flow drawings
You can
learn more at their page.