Re: tool steel
Andrew Hilton
>O-1 Drill Rod is what you want. It's tough, holds an edge fairly well but yet still workable to bend, etc. as you want to. You can then heat treat it easily enough when you've gotten your tool the way you want it before using it.
A piece of HSS (High Speed Steel) will stay sharper a bit longer but is infinitely more difficult to work with in making your own tools (unless you simply want a straight bit to put into another tool like many larger hollowing rigs or braze to it)
Just for doing small hollowing for what you mentioned, the 0-1 Drill Rod is quite sufficient.