Princeton Tec Blast Modification
I like to be able to turn my flashlights on and off using just one hand, and with a lot of twist-on flashlights it can be fairly difficult to turn them on using only one hand especially if the flashlight doesn't feature any surface texturing to enhance one's grip. However, there are ways around this.
In the Blast's case all you need to do is glue some tread stair tape onto the front end of the flashlight using a thick super glue gel.
If it is done right the tape will be hardly noticeable and will not detract from the flashlight's appearance.
This modification can be seen in the below photos: