Lego's 0.002mm specification and its implications for manufacturing (2025)

Older sets had larger foundational and platform pieces which gave a good starting place for new creative builds.

Today, airplanes fuselages, wings, and car chassis are instead built up piece by piece.

It’s hard for my 6 year old to start creative builds that are stable when he hardly has any pieces larger than 2x6 across dozens of sets.

My wife found a huge mixed bin from the 80s and 90s at an estate sale. It really helped.

edit: I know you can get thousands piece brick sets from third parties or random bulk set sales on Amazon... the issue is the random bits are from the current sets mostly with little reuse value, and the bricks sets are from third parties of questionable tolerance compared to real lego. I just want to be able to get a classic 1000-3000 piece set of classic bricks/pieces from Lego proper, even if it's $100-200 total, still way more than 3rd party but maybe not the same margins for Lego as the bespoke sets.

edit2: there are some "Lego Classic" sets that are closer to what I would like to see, this is probably the closest.

https://www.amazon.com/dp/B0B5FMF8BF/

But even then, maybe need that many more bricks that are just bricks... again, there are third party sets that are all block variants that are much bigger/cheaper... would just be nice to be able to get more of those without paying an arm and a leg.

> many sets feel like display models than something you can play with.

That's because they are. There probably never been this many adults building lego than today.

> The Mindstorms/NXT line had huge potential but then just sort of fizzled out.

That's a small niche in today's world, a child is too young for arduino/feather/cyberbrick/whatever.

I haven't seen this push? The new Lego Smart stuff is explicitly "screen free play". There is an app but it's just for firmware update and configuration and you can't even connect it unless the brick is on the charger.

Even when I was a kid, I wasn't keen on graphic designs on the pieces. I liked the uniformity of consistently-colored pieces. Most graphics only make sense in the context of the set they were packaged in. Stickers give the customer flexibility. Use them when you build the set, and remove them later if you take the set apart and don't want them anymore.

Killing Mindstorms was a head-scratcher to me. Hell, there was an entire international tournament built around Mindstorms. I know FLL still exists, but why kill that darling specifically?

NXT still kicks ass by the way. I have a backup of the NXT programming environment somewhere, it can be coaxed into running on Windows 11.

You can even get a model of post-explosion Chernobyl. Not to mention all the sci-fi tie in from Star Trek to Warhammer that real Lego hasn't signed contracts for. But if you want an 60cm Gloriana class, there it is.

Plus Technics-ish sets and bulk boxes that aren't 75% special body panels that only fit that specific model, since Technics itself mostly seems to have been downgraded to the automotive brands advertising department.

Lego’s net profit margin is only about 19%.

They couldn’t lower prices much even if they wanted to.

And then they sued the pants of everybody that tried to do the same thing to them.

Is it? It's not like it's hard to keep producing the pieces to the same original specifications. If they snapped then they snap now.

That’s what I thought when comparing to my childhood sets, but it doesn’t stop my kids from loving them and playing with them.

My kids are learning a lot of cool building tricks from the advanced sets that I never thought of as a kid. Lots of angle pieces, hinges, and creative building.

It has momentum because they haven’t let quality and innovation slide. They know customers will be out with pitchforks if quality drops.

This was all done planned and implemented by this one consulting guy (MCK?), who became CEO after delivering his report from his consulting company, Lego was near bankrupt back then - he started with all this subbranding shitty stuff and the "colorful" bricks and introduced all these many many "single-use-case-bricks" for more and more sets.

I've bought a decent amount of Duplo and Lego kits for my son (currently 3 years old) and it's great value.

I must say, the new smart bricks with all sorts of sensors(color, gyro, distance etc) triggers the inner child in me. I can’t wait to get them for my kiddo and teach him how that magic actually works beneath.

The regular LEGO at this points feels “just plastic” and I won’t feel bad offloading that purchase to AliExpress.

EDIT: I think I also had some dark grey pins, but I don't remember if they were high or low friction

Imho, this is, objectively, not true (anymore).

Pantasy with GoBricks are superior in coloring and fit; Cobi are excellent for things that should not be taken apart anymore (like tank models); Lumibricks are excellent in fit and have amazing illumination solutions that are lightyears (haha) ahead of lego.

We have a set (something with Spiderman IIRC) that attached wheels with yellow pins that allow for better rolling of wheels. The black pins are too tight for this indeed.

The history here is deeper than most people realize. The United States spent fifty years (roughly 1800 to 1853) at the Springfield and Harper's Ferry armories trying to achieve what LEGO now does routinely: parts manufactured to tight enough tolerances that they are truly interchangeable without fitting. In 1853, a visiting British inspector randomly selected ten muskets made in ten different years, disassembled them, mixed the parts, and reassembled ten functional muskets using only a screwdriver. Tolerances of a thousandth of an inch. It was considered impossible by most of the engineering establishment of the time.

The way they got there was by building machines, then using the parts those machines made to build better machines, then using those improved parts to build even better machines. A virtuous circle of transferring skill from human hands to tooling. This is the actual origin story of what historians call the American System of Manufacture, and it's the foundation the entire modern automotive supply chain sits on.

So yes, any competent injection molder holds tight tolerances today. But that's precisely the point: the reason it seems unremarkable now is that two centuries of compounding precision made it so

Also to correct you, LEGO has been making most of the parts for decades, some have had changes due to new materials (which you can read upon online) but besides the ones that remained the same (not really), many new system elements got released in the last decades and new I.P tied elements get released on a yearly basis.

"Precision, for LEGO, isn't an engineering choice, it's a brand promise." - The classic "It's not just x, it's y", just minus the "just".

"One philosophy optimizes for cost, the other for perfection." - Again we see the x/y structure; AI writing often features these forms, eg comparisons (x vs y), conversions (x into y), negated emphasis (not x, but y), etc.

"When you have multiple parts in an assembly, use statistical analysis for tolerance stack-up rather than worst-case math. Traceability matters. Track your defects so feedback turns precision into reliability." - More x/y followed by a short stinger ("Z matters"), and the closing sentence again follows the "x/y" pattern.

For funsies I tossed the whole thing into a purported AI detector and it said 90+% confidence of AI. I don't trust those types of things very much and suspect they have high false positive rates, but I have read that AI writing generally has measurably lower entropy, so maybe it's plausible, and in this case it aligns with my existing beliefs, so it obviously must be true.

Lego does indeed have very tight tolerance, but I don't know if the numbers are in the public domain.

What I don't remember was every kit being made up of so many small, weird pieces.

[1] https://www.lego.com/en-us/service/help-topics/article/lego-...

Let me add this: 4. no spare parts available. So when I break weird Chinese invention the whole set becomes useless without that very special part. It happened few times and I got back to used Lego sets.