[snoman70]

Can't I start with a sphere, or a forging or casting?

Very little of my work is based on a rectangular piece of stock to start...and I don't want to be cutting air.

[keebler303]

I have used this workaround in the past.

Start with square stock.
Make an operation to remove all the stock from the square so it loosely follows your actual stock shape.
Do your normal operations to actually machine the part.
When you post your code, don't post that first operation and then you will not be cutting air.