I decided to go about testing distance with various materials.  The first material I used was velostat.  I taped a strip to a ruler with electrical tape and connected on end to a battery and led, with the other end connected through a paperclip.  the distance was also measurable on the other side.  As I had anticipated, this material produced the largest change in resistance by distance.

Next, I tried copper tape.  Testing the 3 different lengths proved negligible to the LED.

The third was the copper colored conductive material.  The change in brightness also seemed negligible.  Although the increased distance seemed to actually be a  bit brighter, I’m assuming any differences were circumstantial.