Guides

How to build your first MOC

Most builders start the same way: they take parts they already have and build something no set comes with. You do not need special parts, software or a big collection. These are the habits that help a first model turn out the way you pictured it.

Start with what you own

Your first MOC does not need new parts. Rough sorting helps more than a big collection: plates, bricks, slopes and small detail parts in separate trays let you see what you have. A classic first exercise is an alternate build: take one set and make something else from only its parts. Rebrickable lists alternate builds for many popular sets if you want to see what others made.

Pick a subject and a scale

Scale decides almost everything else, so choose it first.

• Minifigure scale: buildings and vehicles that a minifigure fits. City cars are usually 6 studs wide; Speed Champions cars moved from 6 to 8 studs in 2020 for more detail.
• Microscale: a whole building or ship in a few dozen parts, where one plate stands in for a floor or a window.
• Display or sculpture scale: large models where the shape matters more than the minifigure, such as animals, portraits or busts.

Collect reference photos from several angles before you build. Proportions are what make a model recognisable, and photos keep you honest about them.

Know the grid

LEGO® parts follow a few fixed sizes, and once you know them you can plan instead of guess:

• Studs are 8 mm apart.
• A plate is 3.2 mm tall, and three plates make one brick (9.6 mm).
• Five plates stack to 16 mm, exactly two studs. This is why sideways sections fit into a model; see building techniques.

Frame first, surface second

Build a sturdy core, then add the details. Stagger the seams like a brick wall, so no joint runs straight through several layers, and use long plates to tie sections together. Pick the model up often: if it bends or drops parts in your hands, fix the structure before adding anything on top. Once the shape works, refine the surface with slopes, tiles and curved parts, and add detail last.

Learn from official sets

Set designers solve the same problems you will. Building recent sets, or just reading their instructions, is the fastest way to pick up techniques. When you see an angle or texture you like in someone’s MOC photos, try to work out how it was done before looking it up.

Physical or digital

Many builders design on a computer first, so they can use parts they do not own yet and get a parts list for ordering.

• BrickLink Studio: free for Windows and Mac. It has the full parts catalogue, renders and an Instruction Maker, and can send the parts list to a BrickLink wanted list. It is what most MOC designers use today.
• Mecabricks: free and runs in the browser, known for its renders.
• LeoCAD and LDCad: free LDraw editors. LeoCAD is open source and runs on Windows, Mac and Linux.

LEGO Digital Designer, the LEGO Group’s old free program, is no longer supported. Whatever you use, check that each part was actually made in the colour you picked; the BrickLink catalogue lists the colours of every part.

Photograph and share it

Daylight and a plain background are enough for a good photo. Share it on Rebrickable, Flickr or Reddit and ask what others would change. Feedback from experienced builders teaches more than anything else on this page.

If you start from a 3D model or a photo, MOCsmith can give you a first layout to work from. For the parts, see how to buy individual pieces.