This is the better option because not all tools are made of metals that are magnetic. Also, it would be harder to knock off the tool while working.

should make this one pivot.

This will be easier to install and remove from the tools.
Its like a Bandit with an LED in its hook.

I like this desing for its flexibility. In case that it doesn't fit any part of a tool, still you can put it on your finger.

This seems to be the best idea because it can fit multiple tool size widths. My suggestion would be make the "sling" band a firm but flexible rubber with ribs on the back side (not necessarily on the tool side). The rubber would handle the grip concerns and the ribs would allow the band to be adjusted easily to any size. That along with a spring loaded button to adjust the band size would be perfect. Think of a plastic zip tie but adjustible.

This would also work to clip to the temples of eyeglasses - something very practical for a lot of people.

You could try to use velcro to fix it on tools, cause is adaptable to diferent sizes and parts. Faster, easier, versatile and reliable.

The size and design is much mature and reasonable compare to the other at least battery and switch is there. But I don't want too large in size. The cable tie or sling must be strong enough to hold the light in position. It may simply make use of a separated cable tie to fix the light on the tools. A rubber pad build-in at the bottom of the light to create enough friction to prevent the light fall off.

My husband is a plumber and as someone who has spent countless hours holding a flashlight for him, this is a great idea. So, notice 2 things right off: Not sure how much it will stretch, but it either needs to stretch over large pipe wrenches/mechanic's tools or needs a way to change strap sizes. Also, you have to be able to slip this on (at least it looks that way). There are some tools that would be better if you could wrap it around and fasten it because of their shape. I just bought an LED lamp to help with my artwork and it's great. Kudos to the inventor.

Definately the most versatile design.