Keep the bulk order consistent with the sample through written acceptance criteria and checks across production.
Make critical dimensions measurable
Turn accurate dimensions into measurable requirements. Agree the target, allowable deviation and measuring method for critical slots before production. A 100 mm assembly opening and a decorative edge have different levels of importance.
Agree the conditions for comparing colour
Agree how colour will be compared. The same print on clear acrylic looks different against a white background and a black background. Specify the actual background the finished product will use.
Check the beginning, middle and end
Arrange checks across the production run. For an order of 1,000 pieces, agree checks of the first pieces, the middle of the run and the final pieces, then set the sample quantity for the order. Those checks can reveal differences that one completion photograph cannot show.