While it might not be a quality piece that you would want to wear on a daily basis, it would be a good alternative to use to make a costume piece for Halloween as it is much lighter than a chain this size would be and you wouldn't have cold metal against a bare neck if you wore something other than a turtleneck on a windy night and does look more realistic from a distance.
I cut two 20 inch strands of the duct tape and cut each of those strips into three equal parts.
I also cut several smaller pieces about and 1/4 wide and 1 inch long.
On four of the strands, you are going to fold into thirds toward the center of the tape to create each strand. The red in the picture represents the center of the strand. Fold over the left edge over then center, then the right. Repeat on three more strands.
To create each strand in the twisted strands, tape a thin strip of tape the ends of two strands together at one end and then anchor to a table with a heavy book or have someone hold the other end and pull one strand over the other and continue to do so until you come to the end and then then wrap a thin strip of tape around the ends.
Repeat with the other set of strands.
With the two remaining 20 inch strips fold in half of in thirds (I did mine in half - I think it would look better if it had been folded into thirds and tape one end to a twisted end and the other end to the other twisted end.
Tape the two open ends together and you have a DIY Duct Tape Necklace.