Collaborative LEGO Building: Group Projects and Events
Supporting Free Content
When you purchase through our links, we earn a small commission at no extra cost to you. As an eBay Partner, this helps us keep bringing you expert LEGO® reviews and guides. Thank you for your support!
Groups build LEGO together in two ways: everyone builds a module to a shared standard so the pieces connect, or a group splits one large set. This guide covers the main standards (modular buildings, Micropolis, Great Ball Contraptions), how to divide a big set, and how to run a build day.
Groups build LEGO together in two ways. In the first, everyone builds their own module to a shared standard, so the pieces connect into one display at the end. In the second, a group splits a single large set and builds it in parallel. Standards suit clubs that meet again and again; a big set suits a one-day event. Here is how both work.
Build to a shared standard
Fan standards fix a few dimensions and connection points so that modules built by different people, at different times, fit together.
Modular buildings
The LEGO modular building standard puts each building on a 32x32 baseplate (3811). Neighboring buildings connect with a smooth Technic pin (3673) slotted into a 1x2 Technic brick (3700) on each building, one brick 9 studs from the front and one 9 studs from the back. The sidewalk in front is usually about 8 studs deep. Because LEGO's own modular buildings follow the same rules, fan-built buildings can stand in a row with them.
Shopping Street, the 2026 modular building: two buildings on one base, built to the modular standard so it lines up with the rest of the street.
Micropolis
Micropolis is a fan standard for microscale cities. A 16x16 stud module is a quarter of a city block, modules can be 16x16, 16x32 or 32x32 studs, and the base is a 16x16 plate with a layer of bricks on top that includes a 1x2 Technic brick, so neighboring modules can be pinned together. It is a good standard for groups because each module is small and quick to build.
Great Ball Contraptions
A Great Ball Contraption, or GBC, is a chain of machines that pass small balls from one module to the next. The standard keeps it simple: each module receives balls from the left and sends them to the right, its in-basket is 10x10 studs on the outside with an 8x8 opening and no more than 10 bricks tall, and it should accept an average of one ball per second, passed continuously or in batches of no more than 30. See our GBC watchdog guide for keeping a module from jamming at an event.
Train layouts
LEGO User Groups often combine members' city modules and train track into one large layout, agreeing beforehand where the track runs and how modules meet. Current LEGO trains such as the Explorer Train (60470) run on LEGO's Powered Up system.
Explorer Train: a current LEGO City train, a common starting point for a club train layout.
Split one large set
Large LEGO sets come in numbered bags that match stages of the instructions, which makes them easy to divide. Give each builder a bag or a group of bags and the matching pages, or hand separately built sections to different people. Some sets are designed in sections; LEGO describes the Titanic, for example, as built in three sections.
Titanic: a 1:200 scale model that LEGO describes as designed in three sections, a natural way to split the build.
The Lord of the Rings: Minas Tirith, one of the largest current LEGO sets, with plenty of bags to share out.
Running a build day
- Plan the split before the day: decide who builds which bags or modules, and print or share the right instruction pages.
- Give everyone a tray: keep each builder's parts separate so nothing gets mixed between bags.
- Agree the connection points first: for standards, check that everyone's module meets the rules before the day, so the final assembly works.
- Leave time to assemble: joining modules or sections and fixing small mismatches takes longer than expected.
- Mix experience levels: pair newer builders with experienced ones; large sets and standards are both good ways to learn.
Find a group
LEGO User Groups and fan conventions are where most collaborative displays are built and shown. See our guide to LEGO User Groups and our conventions guide.
Related guides
Use Our Tools to Go Further
Get more insights about the sets mentioned in this article with our free LEGO tools