So the CAD drawing I got was for a KJ66. I had to re-design to accommodate a compressor wheel dia of 48mm. All well and into machining... 

I started with the shaft. Here is the shaft mounted and supported by a steady for machining. This was done with effort to obtain the precision required. Turbines turn at 100K rpm and need to be precise….. The finished shaft appears below. I had it polished with 1200 water paper. It came out well and will be checked for concentricity. The compressor wheel appears above.

Next was the shaft housing. I made it out of mild steel as this was the only stock I had in my workshop. The housing was mounted on the rotary table to be drilled. 5  holes drilled and tapped M3 for assembly of the diffuser.

The completed housing, compressor wheel and turbine blank.

The next picture shows the diffuser being machined. This was exciting!!! The intricacy of the machining seemed impossible but it turned out to be simple. The completed diffuser is shown....

So now we need to make the turbine..... try casting it in a home foundry?