Just a consideration. But consider what type of metal. Yea, you can kind of cut anything, sort of, lol
But there's not just brass, bronze, or steel. There's a whole bunch of different grades of brass, bronze, steel etc. Some are a whole lot more pleasant to work with than others, in each type of metal.
In steel, there are so many grades, and so many types of tool steel, like A2, which is easier to machine.
Some brass or bronze may have other elements like tin, or lead. Like Bronze 932 (could be known as C93200 or SAE 660) it has some lead in it, and is real good for making bearings and bushings.
When you really start thinking of a project, research the type of metal, and look at all the variations. You'll see properties, machine-ability etc.
Just a copper, brass, and bronze list to make your head spin, lol:
Bronze Grades Available for CNC Machining - Parts Badger
The lower half of this page is really helpful for a general info on bronze types, applications and such:
Applications: Industrial - Selecting Bronze Bearing Materials
It's pretty much the same regardless which type of metal. If you research the variations of that metal, you can buy small pieces online of what you want.