04 March 2024

LEGO® House Exclusive set review and interview: 40505 LEGO Building Systems

Posted by Caz Mockett

Recently I was lucky enough to attend an online reveal of the latest LEGO® House exclusive set, 40505 LEGO Building Systems, with the opportunity to ask some questions to the set's designers, Stuart Harris (LEGO House Master Builder) and Markus Rollbüller (Senior Designer at The LEGO Group). 

Products in this article were gifted by The LEGO Group; the author's opinions are their own.
This article contains affiliate links to LEGO.com; we may get a small commission if you purchase.

40505 LEGO Building Systems
1211 parts
Released 1st March 2024, available exclusively from LEGO House in Billund, Denmark.

Historical background

LEGO Building Systems is the fifth set in the series of LEGO House Exclusives, which deal with the history of The LEGO Group. The first was 40501 Wooden Duck released in 2020; a brick-built replica of one of the original wooden pull-along LEGO toys. The following year, 40502 The Brick Moulding Machine covered the change from making wooden toys to injection-moulded plastic bricks. The third set, 40502 Dagny Holm - Master Builder, shows a Miniland-scale Dagny at her workshop desk, surrounded by many examples of the models she built for LEGOLAND in Billund. Last year's set, 40504 A Minifigure Tribute was a large-scale version of the popular pirate character Captain Redbeard. 

This year's set features the 3 main building systems which The LEGO Group has in their portfolio: LEGO® DUPLO®, LEGO System and LEGO® Technic. 

Developing the models

Stuart explained that he made the original sketch models which were refined into the final product by Markus, who has now worked on 4 of the LEGO House Exclusive sets. 

The central model is a microscale version of LEGO Town Plan, representing the LEGO System. Stuart told us that the Town Plan sets of the 1950s and '60s offered unlimited creativity because there was no right or wrong way to arrange them, and so the team thought this was an important set to be represented. 

The first sketch model was far too big and had to be reduced in size to give smaller segments to build up the overall layout. Dark Green "espresso" plates (32828) work very well for trees at this scale. 

The first sketch model representing the DUPLO System was a farm, but it competed with the Town Plan in scale and subject matter, so it was decided that a train may be more appropriate. 

Markus remembers playing with DUPLO, System and Technic bricks when he was a child, but since Stuart's sketch model wasn't a real train, he decided to take a deep dive into the world of DUPLO trains to find the best model to represent. The end product is a hybrid of the first two DUPLO trains, 2700 Freight Train and 2705 Passenger Train, both released in 1983. 

Markus made about 6 sketch models, as the wheels were very difficult to get right at this scale. Various elements were tried including the Gollum ring (11010), and 4-stud SNOT bricks which proved hard to build with – plus Markus really wanted to have yellow axles as this would fit the train's colour scheme perfectly. Sketch model No. 5 was a complicated build which came apart too easily. In the end, 1x1 and 1x2 Technic bricks are used in the chassis with yellow frictionless pins which attach to the (newly recoloured) red wheels. The irony of having to use Technic to represent a DUPLO model is not lost on Markus!

Set 851 Tractor was one of the original ideas to represent the Technic System in the brief. Markus suggested that Stuart make a version of 853 Car Chassis for him to develop further. 

Stuart's first version was build studs-up, and was rather large. Markus decided to flip the build and so this representation is build studs-down, which makes the LEGO elements look more like Technic elements, and also offers the perfect attachment method for the little 1x1 brackets (36840) in yellow which are perfect for the seats. The final model was downsized to fit better with its neighbours in the set.

The rear wall in dark bluish gray with pearl gold accents represents the walls of the History Collection in the basement of LEGO House. The gray offers a neutral background to contrast the various models on display, both in the real exhibition space and this scaled-down version. It also holds a secret...

 Turn the model round and you see 19 nanoscale builds of iconic sets from the back catalogue.

The first arched alcove represents:

  • The classic Wooden Duck
  • 700 Automatic Binding Bricks
  • Wooden Fire Truck
  • 651 1:87 Truck (Yellow version)
In the second alcove we have:
  • 127 Complete Train With 3 Wagons
  • 375 Castle
  • LEGO DUPLO 511 Building Set
  • LEGO Technic 850 Fork-Lift Truck
  • 928 Galaxy Explorer
The third alcove shows:
  • LEGO DUPLO 2705 Passenger Train
  • 6285 Black Seas Barracuda
  • LEGO DUPLO 2655 Farm Set
  • LEGO Technic 8480 Space Shuttle
  • 9719 Robotics Invention System (LEGO® MINDSTORMS)
The final alcove displays:
  • LEGO® BIONICLE® 8534 Tahu and canister
  • LEGO® NINJAGO® 70751 Temple of Airjitsu
  • LEGO® Ideas 21318 Ideas Tree House
  • LEGO Technic 42108 Mobile Crane
  • LEGO® Friends 41095 Emma's House
  • An empty spot for you to build a favourite set of your own

Parts of note

The set includes a handful of noteworthy elements: 

Not pictured:
  • 6x Window 1 x 2 x 2 Plane, Single Hole Top and Bottom for Glass in Red (6467937 | 60032) - a new Element ID for an existing element which was last seen once in 2020 in 70436 Phantom Fire Truck 3000 and between 2010-2013 in 6 other sets.


New Elementary was one of several RLFM to attend the online reveal. Here are a few more questions asked during the Q&A.

New Elementary: Do you find it difficult to switch between scales when designing sets, since the mindset for microscale is quite different to minifigure scale or even larger?

Markus Rollbüller: I work in minifigure scale during my day job, but when I build for my own pleasure I often choose smaller scales, so I find it easy to switch.

New Elementary: Are there any building techniques that you are particularly proud of?

Markus: Definitely the upside-down car. The tiny sets at the back too – building in nanoscale was very fun. Also, the wheels on the Wooden Fire Truck - the axles use the 2M bar in red with white Technic bushes for the wheels. I hope that you will share any nanoscale builds you make to fill the gap on the shelves!

BrickNerd: How is the subject of the model determined prior to Stuart building the sketch models?

Stuart Harris: I made the Town Plan first and then thought about what else we might want to include to go with it. I also have a road map of several years of LEGO House sets to come, so I know what will be built each year!

BrickNerd: Has there ever been a set that included elements from all three building systems at the same time?
Stuart: The very first LEGO DUPLO sets in the 1960s came with 8 LEGO System bricks, and plenty of sets include both LEGO System and LEGO Technic, of course. [Update: 7623 Temple Escape included a DUPLO ball as well as System and Technic].

Closing Thoughts

As a big fan of microscale, the main models and the nanoscale ones on the shelves are delightful little builds which replicate their larger counterparts extremely well at such a small scale. The red, yellow and blue accents given to each building system also echo some of the original colours of LEGO bricks, which is a nice touch.

I was initially disappointed that the "DUPLO" brick on the back wall was actually a LEGO System-built version rather than the real thing. The question as to why it wasn't DUPLO was posed at the Q&A, but never answered directly by the team. Having built the set, I have a hunch as to why.

DUPLO bricks are twice as large in every dimension as System bricks, making a real DUPLO 2x2 brick 4x4 System modules along on each side. However, to maintain the gray back wall for the alcove, and the fact that there are only 3 modules of depth available, a real DUPLO brick would not have fitted as it would have stuck out the back, leaving an unsightly yellow section protruding out of the alcove.

As Markus encouraged us to share our own nanoscale builds, I have chosen to make a tiny version of 21309 NASA Apollo Saturn V.  I'm a big space nut, and it was also one of the very first sets I bought myself as I was coming out of my Dark Ages in 2017, finally admitting that I was an AFOL. It meant rearranging the models in the last alcove a little bit, but they all fitted rather nicely in the end.

I think this set is squarely aimed at LEGO nerds like me who love the history of the brick, and as such I hope its intended audience will appreciate the thought and Easter eggs which have gone into every aspect of the design. Even the building instructions contain some fascinating facts about the 3 building systems – as well as mentioning Modulex and Constraction themes! 

Therefore, I don't think the model will be as popular with the general public visiting LEGO House as some of the other iconic sets in the series, such as the Wooden Duck or Minifigure Tribute. 

READ MORE: What are the new LEGO® parts for March 2024?

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  1. I really love the 853 carchassis microbuild! The upside-down us of parts does it!

  2. Great article Caz, thanks.

  3. Here's Lego rewriting History again, calling "original" 2 systems that they initially stole. I'd have more respect for Lego if it was acknowledging its origins.

    1. They do acknowledge Kiddicraft if that’s what you mean and LEGO developed from Hilary Page’s original concept to be what it is today: .

    2. Yeah maybe somewhere if you read the fineprint, but that's not what the story the back of that box seems to tell

    3. All of these systems were after the development of tubes from the original slotted bricks. Although there was a period of tubeless bricks in the earlier sets, LEGO are not reinventing history, it did develop the tube system. Im a huge Kiddicraft fan but I dont think there's always a reason to bring it up.

    4. Wrong. Technics was also a ripoff of Philiform.

      There's no reason to bring it up unless they're talking about Lego's history.
      Also there's a reason for us to keep bringing it up, because Lego is certainly not happy that other brands exist. I keep being reminded it when customs seize my perfectly legit sets (like, Sembo) from China because Lego works along with them.

    5. I had never heard of Philiform before now, but looking it up the comparison to Technic definitely is more of a stretch—while they were achieving similar things with use of things like axles and gears to create movement, Technic is hardly a direct copy of Philiform's parts or system (unlike early Lego copying Kiddicraft, or Sembo pretty much directly copying existing Technic parts).

    6. It's never YOUR interest to be against "copying" in the LEGO world anyway. Other brands are full of great parts that LEGO doesn't have, just imagine now that maybe you'll never gonna get them as LEGO because they've been patented.

      Imagine not getting 1x5 plates (that LEGO did try to patent lol) because another brand had patented them.
      And if you're gonna say that "1x5 plates" aren't a revolution, they're just basic plates, yeah totally. Same thing with "the tubes" that weren't any revolutionnary. In fact, side notches on anything "1 by x" is a lot better than stupid tubes (as tubes require hollow studs, that LEGO doesn't like because it doesn't show their brand, while side notches accomodate for all studs). Large tubes are ok for bricks, but that's never what we're all interested in.

      I used to be a purist, now I'm all in "the bricks system", which I would sum up as a set of metrics and rules, that LEGO didn't "invent", and also some (like colors) that LEGO did "invent", but that's called History and having to cope with that isn't called copying, it's called backwards compatibility.
      And in that "bricks system" trust me that there exists better (and worse) than LEGO, better subsystems (like, brackets, slopes), better quality (like, parts without injection marks, or parts moulded as they should have been).

    7. That sounds interesting. You should start a blog where you can write all this down as much as you want. Somewhere else.

    8. Lego calling them something like "the two original systems" (paraphrasing) is like Nike saying the Waffle Racer is " the original shoe model". With that phrase they're not claiming to have invented shoes, just talking about the first ones from their company. Likewise, I find absolutely nothing objectionable to Lego talking about their first systems. They might be avoiding talking about who invented what, but they're not lying about it.

    9. The comparison with Nike doesn't work, as Lego didn't copy "interlocking blocks", they existed way way before, way before Kiddicraft. They copied the Kiddicraft brick. What defines the Lego system the most, which is metrics, is something we owe to Kiddicraft.
      What you may argue that Lego created isn't the tubes, but rather the 1/3 plate division (and I'm not even sure about that).

      Blocks + metrics = "Lego" system. Lego as a brand is something else, it's an image, it's the symbolic minifigure, and much more. But the Lego system is the Kiddicraft system, and they didn't invent it.
      In a hundred years, "Lego's" will still be around as many many more parts, but you know what's not gonna change? The metrics of a brick.

      Lego also created their own bricks, and where is Modulex now? That's right, it proves that metrics and compatibility is key.