One of the things that makes Lego so great is the ability to rebuild sets into something new and different. However, I know that sometimes TLG uses large pieces to lower costs and/or build complexity. Some examples:

It seems to me that some part choices are quite strange. For example, 7346 - Seaside House contains 2 1x2x2 bricks and 28 regular 1x2 bricks in medium blue. It doesn't seem like the double height bricks provide a much simpler or sturdier build, and the part is less reusable. I would have rather seen 1x2 bricks used throughout, especially since this is a Creator set, which focuses on being rebuildable.

I also found it strange that they chose to use 1x2x2 bricks in two places, but kept 1x1 bricks stacked 5+ high in others. It seems that if the goal is to create a sturdier model, replacing these stacks with 1x1x5 bricks would have been a good place to start.

So, I guess my question is: what goes into the decision of which specific parts to use in a production Lego model?

  • 1
    Your example of 7346 seems very bizarre indeed since it would also mean one less part in the set, reducing the production cost.
    – Joubarc
    Feb 17, 2013 at 10:31
  • 2
    @Joubarc Maybe the 1x2x2 happened to be available to the designer in the right color, and the designer decided to include a couple for the sake of "getting the piece out there"? It's not really important to this set but I could see it being useful, and it's a fairly rare piece...
    – KRyan
    Feb 20, 2013 at 16:01
  • 1
    That plane nose would be ideal for some custom bullet train models as well.
    – diynevala
    Oct 18, 2015 at 5:58
  • I suspect this question would be clearer if you concentrated on examples like the 7346 set; large pieces that do not have a different appearance than combinations of several smaller pieces. After all, at least the look of 54092cx1 is rather impossible to exactly replicate with the same curvature and "streamlinedness" when using smaller pieces, and while the outside of 6082 can be achieved with normal bricks, BURPs are often used as structural components whose interior space is used, as well. Dec 21, 2016 at 19:22

2 Answers 2


Some of the reasons (including some you've mentioned):

  • To make building easier / sturdier, so that the set is more suitable for its intended age range
  • The larger pieces are sometimes cheaper than the component pieces would be
  • The component parts may not be part of the current inventory of parts available to designers
  • To make the build interesting
  • To provide an interesting variety of parts

In the case of the set you mention (and this is pure speculation) it is possible that 1x1x5 bricks are more expensive to make or that they were unavailable in the right colour at the time the set was designed. At the same time, the designers might have felt that the 1x2x2 bricks reduced the part count to the extent that the set was viable for the intended market.

  • It looks like your hunch about the 1x1x5 bricks may be correct. I checked bricklink, and these don't seem to exist in medium blue.
    – jncraton
    Feb 16, 2013 at 14:07
  • A non-existing part is certainly a good reason for the 1x1x5, but the 1x2x2 makes no sense whatsoever to me.
    – Joubarc
    Feb 18, 2013 at 15:22

One aspect could be to make the models more interesting to build.

As far as I can see, Lego is at it's core a kid's product.No offense. I love it too and last time I check I didn't qualify as a kid.

And a varied set of bricks seems to me more appealing to "the kid" than a uniform engineering-streamlined set of bricks.

Then, I don't know the design process for Lego models, but maybe the designers just pick and choose what they feel like. (Essentially following what I described above.)

Disclaimer: Of course, pure speculation on my part.

  • 1
    The designers are certainly the key actors in picking the parts required for the set they are designing, but they aren't free from constraints, far from it. As such, the example of the 1x2x2 bricks in 7436 is really weird since the designer had to face the extra cost of including an additional part instead of just using some more regular 1x2
    – Joubarc
    Feb 18, 2013 at 15:20

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