I noticed recently that hidden Lego pieces in many sets (I did not check them all of course) have completely different colours than those are visible. They usually differ from not only the colour of the visible parts but they seem to be somewhat randomly coloured. Why aren't they coloured the same as the other pieces? Is it cheaper to use base colours?

Example: The statue of liberty set (21042) practically has two colours visible (green and sand), however inside there are red, yellow, blue and black pieces as well.


2 Answers 2


Using different colors on the inside makes the instructions easier to follow. For example, in the case of the Statue of Liberty that you mentioned, if the entire model was sand-green, it would be easier to make mistakes in 1.) following the printed instructions, 2.) finding the pieces in the pile of loose elements, and 3.) attaching the pieces to the model under construction.

Remember that LEGO sets are primarily designed for children, so LEGO puts a lot of testing and effort into making the instructions frustration-free. Using different colors is beneficial even for older LEGO fans who may start to have failing eyesight and would have difficulty finding pieces and seeing the instructions clearly.

As far as which colors are chosen for the interior, they are something that contrast with the main colors of the model, easy to see in the instructions booklet, and easy to find in the pile of loose elements. Another thing that may be taken into consideration is that if the set has instructions for alternate models and what colors those alternate models would need (i.e. LEGO Creator 3-in-1 sets).

  • 1
    "As far as which colors are chosen" - one more aspect is - what colors are in production at the same time, for other sets. Saves money.
    – Mołot
    Jun 6, 2018 at 10:09
  • Easier building: If all bricks where the same color you would have a harder time to see where one brick ends and another starts.
  • Availability: In some cases parts are only available in specific colors. LEGO could produce them in new colors, but for inside parts that is not needed so they reuse the existing color(s).

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