There are a lot of great Hex Bit Handle models out there but I'm learning Fusion360 and decided to give designing my own a go (I have included the Fusion360 file in case you'd like to make any modifications). 

I had a few things in mind during the design process: 

• First, I wanted a contoured handle that wasn't too long but long enough to hold onto comfortably, so I went with a length of 60mm.
• Secondly, I wanted to ensure that the hole was deep enough to provide proper support for longer extensions, so I used a depth of 13mm which has worked great for standard bits and longer inserts.
• Lastly, I wanted the bits to fit snuggly but not so tight that pliers were needed to remove them. I made the hex hole 6.44mm across which seems to work just right.

IMPORTANT: The provided model works great for me, but things can vary from printer to printer, so I recommend starting with the original model then scaling it up or down in 1% increments as needed.

Printing:

• Supports: None
• Infill: I recommend at least 25% or higher.
• Layer Height: .2mm
• Material: PLA