all right, couldnt find good info anywhere else, and I know the 3d guys must know something. I realize translucent covering is lighter, but by how much? what brand is lightest? My favourite is ultracoat, but my guess is it is heavy . I was almost thinking along the lines of adhesive-less covering and balsarite etc...
note... this is for a laser 3d
if you have any other good "jenny craig" tips post em here... lets try to make a resource out of this thread as I couldnt find the info elsewhere on the site. Im going to go to some hobby sites and research claimed weights for various coverings.

heres an ok chart http://www.fatlion.com/sailplanes/weights.html
some info from tower

coverite 21st century is .25 oz/ft, same with translucent covering

monookote is .2 oz/ft, trans is same, except for clear which is .5 (mistake?)

Nelson lite film is supposed to be 1/2 the weight of regular covering. The Ultracote on my sledge weighed in at 5 ounces for the finished covering job. Something to remember is the lighter covering is not as strong, and some of these airplane use the covering for strength. On the Laser 3D you will only save 3-4 ounces, but is the weight savings worth the sacrifice in strength? Tom

well, the biggest strength contribution from covering is torsional rigidity in wings. Even cellophane on my electrics with no spars (only cf LE and TE) is all that is needed to make wing rigid enough