Ehsan,

Good points. I was going to mention that I also am generally not wild about fast set epoxy's due to their more crystalline (non plastic) nature once cured and as they age. So you wind up with a "cracking" stiff wing. Once one joint fails though one ends up with a faulty wing.

Wood glue is less dense than fast epoxy (probably even slow epoxy) but one tends to use a little more due to its low viscosity. Used carefully though I think it's a fair bit lighter as much of it evaporates. With epoxy, the weight applied is the weight used. I actually find myself using wood glue more and more as I no longer use CA as much as I used to. Wood glue has become very good and has improved drastically in the last 30 years. Then again, so have epoxy resins...

David