Question for head porters

I use air... A very small diameter straight die grinder. I have a small valve to regulate the speed by airflow. I had a Makita, but the way I held it covered the air vents and I seized it...lol. You can also go to any hardware store and get a dial type light controller... Like you have in dining rooms to dim them... Wire that into the tool's cord, and you can slow it down too. Some bits and materials like slower speeds... Especially when polishing, and that speed control gets handy.