These are one of the main tools for carving. You use them with burs which normally have diamond grit coating them. You can buy burs in lots of different sizes, shapes and grits.
You can run handpieces at a variety of speeds which is controlled by a foot pedal or a bench top dial.
Hand pieces are divided into two main categories – micromotors and flexshafts. Micromotors have the motor in the handpiece and flexshafts are when the handpiece is connected to the motor via a long flexable shaft.
There are a lot of different brands for micromotors which range from $200 – $1600 +. I have two cheaper ones which suit my work perfectly – ( a SAESHIN and a Micropro )
I mainly carve smaller pieces so you would prob want a larger handpiece for bigger pieces.
The main company that sells flexshaft is Foredom. You can buy them almost everywhere so shop around. I have one that I use when I need more power than my micromotors. You can get a wide variety of handpieces for them. I have a few different handpieces. Two that take different sized collets and one with a chuck so I can use tiny 1mm drill bits.