While these parts are totally adequate for scratch building, I found flash evident on the side stacks and corner irons. This is something I never encountered when these parts were produced directly by Grandt. I have been using these sets for well over 30 years. The presence of flash is not a good sign that you have mastered injection molding but might also reflect that the Grandt's failed to tell you something important about their tooling. Either way, the standard you should be striving for is properly formed flash- free parts. Better luck next time.