I'm in the process of glassing and painting my first pattern plane. I purchased a video from Don Ramsey on the proper techniques on glassing and painting a pattern wing. It is a great source of info. In that video he weights the wing panels at each stage of the process. At the end of the process he increased the wing panels by about 33%. In my case, I just finished glassing the entire plane. I increased the weight of each component so far by 20% or so. Don increased his by a little less than 20% after the glassing stage. Since this is my first time I feel like I'm in the right ball park. I estimate I will increase the weight of my plane by less than 35%. If you choose to glass and paint I would bet you will increase your plane by 35% also. Hope this helps.