3M spray adhesive shold be easily found at a home center. It is a contact adhesive, meaning that both surfaces receive the adhesive and that when they touch, they are bonded and no drying time or compression is needed.

A word of caution... I used 3M many times on foam core wings many years ago. It would be wise to ensure that any spray adhesive chosen doesn't attack foam.

To keep the sheet and core seperated while locating the sheet... some strips are needed. I may have mis spelled "venition blinds", I refer to window shades that open and close. Years ago they were metal and now are almost allways plastic. The strips from a discarded window shade work very well as standoff strips keeping the core and sheeting seperated until contact is desired.

A really nice result of using spray adhesive is the speed factor. Once the sheets are prepared, the four skins can be glued onto the cores in a matter of a few minutes and immediately be ready to trim and apply leading and trailing edges and tips. I've often done that with spray adhesive as well.

Another important note: The balsa strips must be prepared as a sheet as several describe above. I don't think spray adhesive would work for individual sheet application as there is no repositioning once contact is made.

For this reason, sanding should be done prior to the glue up of the strips. Fit them together with masking tape on the back side, place on flat surface and sand. Then flex open the joints and using a very small brush, lay 15% thinned titebond on the edges, press flat and wipe excess glue away with slightly dampened rag. Weight down to dry. As others have said, making the sheets up, sanding should be done prior to gluing joints as the hard joints will not sand even to the surrounding balsa.