I am a SolidWorks user with a 3D Connexion Space Mouse on my left hand and a cordless Microsoft Optical mouse on the right. My right hand is bordering on repeteitive stress injury and I want to pursue alternatives. The Microsoft Optical Trackball looks promising as it uses the thumb to control the ball with the other controls more or less normal. I would greatly appreciate any comments from users of this device or similar to reduce the gripping action required with a mouse.