Ive been using the slow cure epoxy for years. I use Pro Build, mainly due to its what I use when doing layups from molds. Its thin and spreads easily. Any other brand will do.

First thing I do is get the sheeting together and tap together enough to cover each side. Then, I fold the taped joint back so the bare balsa is showing and I use wood glue to glue in that joint. Fold it back down and then do each joint that way. Reason is, wood glue is easier to sand than epoxy If you didnt do this step, epoxy would uzzz out the seam and then you get a hard seam surrounded by soft balsa. When you sand it, the seam will show when you cover it. Just a trick I learned over the years.

Then do as the othes say. Lay the sheeting in the shuck, tape side away from wing core lol. Then coat with epoxy, add the core, then epoxy and then the other sheet, then top it off with the skin. I use a couple of 2 x 10's and 3 large car batteries for weight. The epoxy gives you time to arrange the skins before it sets, the weight holds it all in place so you dont get any warpage. Also, the epoxy makes the wing ...solid...It will never peal off or get an air bubble under it.

Thats my contribution All the above means are perfectly fine for skinning cores. Just pick the one that you feel comfortable with and go with it.

WBG