Two stand out in my mind. My 3rd build in the early 80's the red box TF P-40. Took forever.. sand, sand, sand. getting the crapy plastic cowl together with the sharks mouth decal took longer then my first entire build. The worst part was the flight life was inversely proportionate to the build time. Go forward 20 years and build a GP sales P-38, the parts looked like they were cut out with a dull steak knife and the glass seams were even worse. Maybe the product is better now but a few years ago it redefined "A builders Kit" Good news is I learned from my P-40 mistake, flew the 38 twice landed it, sold it and the new owner planted it not to much later.