I have a great, nice flashlight Sofirn HS42. But the grip might be better. So I have used my 3D printer to do it.

Features:

• Nice feeling in a hand
• Easier and faster finding a good grip with tour hand in a pocket
• A flashlight can be put to light stright up - it gives a nice soft light in a room, spreading from a ceiling 
• A finger in a hole gives a firm grip and ensures it would not fall down from a hand.

Printed in PLA with a brim. Used supports for a finger hole. After printing it is good to use a sand paper for the hole and brim residues to make perfect feeling in a hand. I made it tight to avoid any movements, so used some force when sliding in.