One method I tried was to take a small piece of paper and fold it so it sits at 90 degrees. I install a winglet then place the paper under the wing to support the winglet. The tacky glue gets stuck to the paper. It also draws some glue away from the foam.
I’ve been toying with the idea of having some groves so that a temporary brace can be installed while the glue is drying. It could be removed later. That is easy enough with laser cutting.
I found a great technique which is to place the wing upside down on a glass or other small object. The winglets hang down and gravity keeps them well aligned .
I tried this on a group of children last night and found that they were able to carry it out without any problem.
The other challenging glue joint is the connection between the tailplane and the tailboom/motor stick. The challenge here is that in my test kit, the curvature of the tailplane is in the wrong direction. I looked at pins, and a couple of other ideas. I personally love pins but I don’t think it belongs on this beginner plane. A V-Tail is something I’m exploring too. With that, you can get both vertical and horizontal stabilizers in one step. I took the horizontal tailplane and scratched it so it could be folded into a V. More on that later.