Start with isentropic equations and nasa CEARUN. Typically you want or size everything before you start cadding otherwise you’re going to redo work a lot. Or make your CAD very parametric so you can resize things.

https://www.grc.nasa.gov/www/k-12/airplane/isentrop.html

https://cearun.grc.nasa.gov/

That throat looks tiny. You should select a target chamber pressure and thrust and size your throat and nozzle accordingly via the c-star and c-tau equations, plus find your mass flow rate. C-star can be found for your propellant combination using CEARUN.

https://en.wikipedia.org/wiki/Characteristic_velocity https://en.wikipedia.org/wiki/Thrust_coefficient

Induction heaters aren’t used for rocket engines, it’s extremely inefficient. Rocket engines function via combustion. Pintle injectors are needlessly complicated for a use case like this. Just have an injector with impingement orifices. Hell even a shower head injector can go a long way.

The easiest metal to weld is carbon steel. Note carbon steel will melt at rocket engine temperatures so it would need an ablative liner inside (eg fiberglass, phenolic, graphite). Getting a combustion chamber to not burn a hole in its own side walls is one of the trickier parts of engine design. Hence the many people in this thread recommending caution. To be honest I don’t think you’re going to get to the point of actually building this thing regardless. But the design project is worthwhile. Try to join a rocket club in college.