I've thought of a number of ways to extend a blade, I just haven't thought of too many ways of getting it back in the hilt afterward! There have been a few attempts posted here for different sorts of designs.
The main issues I see are:
extend the blade - difficult
illuminate the blade - easy
swing the blade - medium
retract the blade - extremely difficult
dueling blade - jedi master
do all of that fast and silent - ?????
I think the real trick will be designing something that can extend then can allow at least some light dueling.
Most ideas I've had would be extremely light so at least the physics would possibly a lot more "realistic." I have some ideas that might work for retraction conceptually, but I'm not sure they'd be very practical or reliable.