If joining large parts, like wings, you can put masking tape around the area you don't want epoxy on. After joining wings and wiping the joint with alcohol on paper towel, peel off the tape.

I have also put epoxy into a syringe for application, but it is only good once. You can get a "needle" tip that is rounded and dull (I think it is for injecting meds into I.V. tubes). This tip has a larger I.D. that will pass thick glues quite well.

Once I put mixed epoxy into a sandwich baggie and cut off one corner. Squeeze the glue out like a cake decorator does with frosting. It was rather messy getting it into the baggie, but still worked OK.

As stated by another post, use slow set (30 or 45 min) to give you some working time.

For most applications, I just use popsickle sticks to mix and apply. If I need a smaller applicator, I just cut a piece of scrap wood to the size I need.