Step 1: What you need
D-Ring Carabiner (3-5 inch carabiners work best, bigger is better. They don't need to be "load bearing")
Hex Nut (large enough to slip into the carabiner and go all the way around. The flat sides need to be big enough to drill a 1/4in hole into)
Short Magnetic Bit Driver (The kind you'd use in a power drill)
You'll need the following tools
1/4in Drill Bit
Square or Triangle needle file (must fit into a 1/4in hole)
J-B Weld (or what ever you prefer)
Drill or Drill Press (Not Pictured)
Step 2: Preparing the Nut
Drill a 1/4in hole into the nut.
Once the hole is drilled you will need to file the hole into a hexagon that matches the bit holder.
Be patient, this takes a while. You want the hole to be as tight as possible. You should nee to use the hammer to persuade the bit holder into place.