What is a MOC?
MOC stands for My Own Creation: a model someone designed themselves instead of building it from a set’s instructions. The word comes from the adult fan community and now covers anything from a ten-part spaceship to a whole city layout. If you have ever built something from a pile of loose LEGO® bricks, you have built a MOC.
Words you will meet
| Term | Meaning |
|---|---|
| MOC | My Own Creation, a model of your own design |
| MOD | An official set that a builder has changed, for example a longer train or a rebuilt interior |
| Alternate build | A different model built only from the parts of one set |
| AFOL, TFOL, KFOL | Adult, teen and kid fan of LEGO® bricks |
| LUG | A local or online user group of builders |
| SNOT | Studs Not On Top: building sideways or upside down (see building techniques) |
| Greebling | Small parts added to a surface for texture, like the panels on a spaceship hull |
| Bley | The bluish greys that replaced the older greys in the mid-2000s |
| Studio file, LDraw | The two common file formats for digital models: .io from BrickLink Studio, and .ldr or .mpd from the open LDraw system |
Where builders share MOCs
- Rebrickable is the largest library of MOC instructions, free and paid. Its Build feature compares your sets with a MOC’s parts list and shows what you are missing.
- BrickLink, the parts marketplace, hosts a gallery of models made in its free Studio software.
- Flickr, Eurobricks and Reddit’s r/lego are where many builders post photos and talk through techniques. Blogs such as The Brothers Brick feature standout models.
- LEGO® Ideas takes fan designs as proposals. One that reaches 10,000 supporters is reviewed by the LEGO Group and may become an official set.
“MOC sets” in online shops
On marketplaces, “MOC” often labels a boxed kit made by another brick manufacturer, not by the LEGO Group. A few of these kits are licensed from the designer; many copy fan designs without asking. If you like a design, look for the designer’s own page. Buying their instructions and collecting the parts yourself is the way to support them.
Are MOC instructions free?
Many are. Designers on Rebrickable choose whether to share instructions for free or sell them, usually as a PDF with a parts list. Some designs are shared only as photos, which experienced builders use as a reference to work out the build themselves.
Ready to make one? Start with how to build your first MOC.
More guides
- How to build your first MOC
Scale, the brick grid, building a sturdy frame and the free software builders use.
- Building techniques: SNOT, offsets and greebling
SNOT and its parts, the five-plate rule, half-stud offsets, greebling and “illegal” connections.
- How to buy individual pieces for a MOC
Pick a Brick, BrickLink and the other places builders buy parts, and how to spend less.
- How to make building instructions for your MOC
What good steps look like, the tools designers use and where to share them.
- How to make a brick mosaic from a photo
Size, colours, dithering, bases and buying the parts for a custom mosaic.
- Turning a 3D model into a brick model
What conversion gets right, why it falls apart and how to finish the model by hand.