What is a LEGO MOC?
By MOC Instructions · Updated · 8 min read
MOC stands for “My Own Creation”. In the LEGO world, a MOC is any model designed by a fan rather than by the LEGO Group: a custom build made from regular LEGO pieces, often with its own step-by-step instructions so that others can build it too.
What MOC means
The word comes from AFOLs (adult fans of LEGO), who have used it since the early online fan forums of the 1990s to tell their own designs apart from official sets. Today you’ll see it everywhere LEGO fans share their work: on Instagram and TikTok under #legomoc, on sites like Rebrickable and BrickLink, and at LEGO fan conventions.
A MOC can be anything. A tiny six-piece chair counts, and so does a castle with thousands of bricks. What makes it a MOC is only that a fan designed it. Some designers keep their MOCs to themselves; many publish instructions so that anyone can build a copy, either for free or for a small price.
MOC vs official set vs MOD
Four terms get mixed up a lot. Here’s how they compare:
| Designed by | Pieces | Instructions | |
|---|---|---|---|
| Official LEGO set | LEGO Group designers | Genuine LEGO, in the box | Printed booklet or the LEGO Builder app |
| MOC | A fan | Genuine LEGO, from your collection or BrickLink | Made by the designer, usually digital (online or PDF) |
| MOD | A fan, starting from an official set | The set, plus extra or swapped pieces | Often just photos or a short guide |
| "MOC kit" from a third-party brand | Often a copied fan design | Compatible bricks, not LEGO | Printed booklet |
Real MOC examples
The range is huge, even from a single designer. Here are six from this site, from a 31-piece Christmas Tree to a 375-piece Charizard:
Charizard
375 pieces · 20 x 27 studs
Among Us Crewmate
123 pieces · 7 x 7 studs
Claw Machine
53 pieces · 6 x 6 studs
Drum Kit
72 pieces · 12 x 6 studs
Christmas Tree
31 pieces · 5 x 5 studs
Couch
37 pieces · 8 x 3 studs
Characters from games and films are popular MOC subjects because LEGO doesn’t make a set for every character. Everyday objects in miniature (furniture, arcade machines, a drum kit) are another big family: they’re small, quick to build and easy to display together. You can browse them all by category.
MOC words you’ll come across
- AFOL
- Adult Fan of LEGO. Most MOC designers are AFOLs, and the word MOC comes from their community.
- MOD
- An official set modified by a fan, as opposed to a MOC designed from scratch.
- Stud
- The round bump on top of a LEGO piece, and the unit builders measure with: one stud is 8 mm, so a 20 x 27 stud model is about 16 x 22 cm.
- SNOT
- "Studs Not On Top": building sideways or upside down so smooth surfaces face out. It's how MOCs get their curves and clean faces.
- Tile
- A flat piece without studs, used for smooth finishes.
- Greebling
- Adding lots of small pieces to a surface for texture and detail.
- Minifigure scale
- Built to the size of a LEGO minifigure, so the model fits into a LEGO city or scene.
- BrickLink
- The largest marketplace for individual LEGO pieces, where independent stores sell parts by number and color. Owned by the LEGO Group.
- BrickLink Studio
- A free program to design LEGO models in 3D and make instructions. Most MOC instructions today come from it.
- Wanted list
- A shopping list of parts you upload to BrickLink so it can find the stores that have them.
- Part number
- The number that identifies a piece shape (for example 3001 is the classic 2 x 4 brick). Together with the color, it tells you exactly which piece to buy.
How to read MOC instructions
Most designers build their MOC in BrickLink Studio, check that every piece really connects, then use its instruction maker to split the build into numbered steps. Some build with real bricks first and model it afterwards. Either way, the pages look just like an official LEGO booklet.
Every step has the same three parts:
- The step number, top left.
- The parts box: the pieces to add in this step and how many of each (here, one black round brick).
- The model, with the new pieces outlined in red so you can see exactly where they go.
On this site you can follow every page in your browser, and spin the interactive 3D model when a step is hard to read from one angle.
How to build your first MOC
1. Pick a small model
Your first MOC should be small enough to finish in one sitting and to source in one order. These are good starting points:
| MOC | Pieces | Steps (pages) | Size | Build time |
|---|---|---|---|---|
| Chair | 6 | 4 | 2 x 3 studs | about 10 min |
| Park Bench | 10 | 6 | 6 x 3 studs | about 10 min |
| Bellsprout | 10 | 8 | 5 x 3 studs | about 10 min |
| Fire Hydrant | 12 | 9 | 2 x 3 studs | about 10 min |
| Gumball Machine | 25 | 14 | 3 x 4 studs | about 10 min |
| Arcade Machine | 28 | 12 | 4 x 6 studs | about 10 min |
Build times are estimates for an adult following the instructions. When you’re ready for more, the MOCs under 100 pieces are all rated easy.
2. Check what you already have
Each MOC page shows its piece count and parts list. Before buying anything, go through your collection: small MOCs mostly use common bricks, plates and tiles that many LEGO fans already own. If you only miss a piece or two in a spot nobody sees, a different color works just as well.
3. Order the missing pieces
BrickLink is where most builders buy individual parts: thousands of independent stores sell pieces by part number and color. Upload your list of missing parts as a wanted list, and BrickLink’s Easy Buy suggests the stores that have them. The LEGO Group also sells single pieces directly through Pick a Brick, with a smaller selection.
4. Build it
- Sort the pieces by color into small bowls or a tray before you start. It makes every step faster.
- Check each step against the picture before moving on. A plate shifted by one stud shows up three steps later.
- Use the 3D model when a step is hard to read: turn it around to see the hidden side.
How much does a MOC cost to build?
It depends mostly on what you already own. For small MOCs like the ones above, you may already have most of the pieces, and the instructions here are free. When you do buy parts, common pieces in common colors are usually inexpensive on BrickLink, while rare colors, printed pieces and large specialized parts cost more. On small orders, shipping is often the biggest line, which is why the store count matters more than the price per piece.
Bigger MOCs add up faster: a model with a few hundred pieces is closer to the price of a mid-size official set, and it’s worth checking your collection carefully first.
Who designs the MOCs on this site?
Every model on MOC Instructions is designed by BrickProject, a lifelong LEGO fan who shares his creations on Instagram. Each MOC is rendered in 3D from four angles and comes with the full set of step-by-step instructions, free to follow online.
Prefer paper? MOC Instructions Pro adds a printable PDF of every MOC, the full parts list, a one-click BrickLink wanted list and the original Studio file.