LEGO Parts Reference & BrickLink Guide

What the Parts Lab Is

The Parts Lab is the reference section of The Earl of Bricks. It exists for builders who have moved past following instructions and started designing their own creations — and who quickly discover that the hardest part of a MOC isn't the design. It's finding the right parts.

When you build from a LEGO set, every piece is in the box. The colors match, the quantities are right, and if something's missing, LEGO's customer service will send a replacement. MOC building is nothing like that. You need to know exactly what part you want, what color it comes in, whether it's still in production, how much it costs, and where to buy it. You need to understand part numbers, color codes, and the difference between "new" and "used" in a marketplace context. You need to know when it makes sense to buy specific parts one by one and when it's cheaper to buy a bulk lot and sort through it.

This section covers all of that. It's a living reference that grows as the site's builds and reviews reference more parts, more techniques, and more sourcing strategies. Whether you're placing your first BrickLink order or optimizing a 5,000-piece parts list for a flagship MOC, the information here will save you time, money, and frustration.

BrickLink: The Builder's Marketplace

BrickLink is the world's largest online marketplace for LEGO parts, sets, minifigures, and related items. Founded in 2000 by a LEGO fan, it was acquired by the LEGO Group in 2019 and continues to operate as the definitive platform for buying and selling individual LEGO pieces. If you're serious about MOC building, BrickLink is not optional — it's essential.

How BrickLink Works

BrickLink is not a single store. It's a marketplace of thousands of individual sellers, each maintaining their own inventory of LEGO parts. Think of it like eBay, but exclusively for LEGO, with a catalog system that makes the Library of Congress look casual. Every piece LEGO has ever produced is cataloged with a unique part number, available colors, known appearances in sets, and current market pricing.

When you need parts for a MOC, the process works like this: you search for a part by number, name, or category. BrickLink shows you every seller who has that part in stock, in every available color and condition. You add items to your cart, and because items come from individual sellers, you'll place separate orders with each store. Each store ships independently — which means shipping costs multiply if you're buying from many different sellers.

Part Numbers: The Universal Language

Every LEGO element has a unique part number. A standard 2x4 brick is #3001. A 1x1 round plate is #4073. A minifigure head is #3626. These numbers are the universal language of LEGO building — they're how BrickLink catalogs parts, how Stud.io identifies elements in digital designs, and how builders communicate precisely about specific pieces.

Part numbers matter because LEGO produces parts that look similar but aren't identical. There are multiple versions of a "2x2 slope" — different angles, different profiles, different connection points. Saying "I need a 2x2 slope" isn't specific enough. Saying "I need part #3039" tells any builder or seller exactly which piece you mean, eliminating ambiguity entirely.

You'll find part numbers printed on the inside of most LEGO elements (look on the underside of bricks, inside the stud tubes). BrickLink's catalog is the most comprehensive reference for matching physical parts to their numbers — more complete than LEGO's own public-facing systems.

The Color Problem

LEGO has produced over 200 distinct colors across its history, and BrickLink catalogs every one of them. This is where things get complicated for builders. "Gray" is not one color — it's at least four: Light Gray (discontinued), Dark Gray (discontinued), Light Bluish Gray (current), and Dark Bluish Gray (current). LEGO changed its gray palette around 2004, which means pre-2004 sets use different grays than modern sets. They look similar in photos but are visibly different in person.

The same issue applies to brown (old Brown vs. Reddish Brown vs. Dark Brown vs. Medium Nougat), blue (multiple shades with subtle differences), and green (classic Green vs. Bright Green vs. Dark Green vs. Sand Green vs. Olive Green). BrickLink's color guide, with actual part photos in each color, is the definitive reference for distinguishing these shades.

For MOC builders, color accuracy matters enormously. A single wrong shade of gray on a facade breaks the visual consistency of the entire model. Always verify color by BrickLink color name and number — never by what you think a color looks like on screen. Monitors lie. Part photos under different lighting lie. The BrickLink color ID never lies.

Pricing and Buying Strategy

BrickLink pricing varies by seller, condition (new vs. used), quantity available, and rarity. Common elements — standard bricks, plates, and tiles in popular colors — are inexpensive. A new white 2x4 brick might cost $0.05 to $0.15. A rare color of a specialized element can cost $2.00 or more per piece.

The key to cost-effective BrickLink buying is consolidating orders. Because each seller charges separate shipping (typically $3–$8 for domestic US orders), buying 10 parts from 10 different sellers means paying shipping 10 times. The smart approach is to find sellers who stock multiple items on your parts list and place larger orders with fewer stores. BrickLink's "Wanted List" feature helps with this — you upload your full parts list and the platform identifies which sellers can fill the most items.

A few more buying tips from experience:

• "New" on BrickLink means unused — the part has never been assembled into a build. It may or may not come in original LEGO packaging. It's simply a part that came out of a set bag and went directly into a seller's inventory.
• "Used" means previously assembled — the part was built into a set and later disassembled. Used parts are significantly cheaper and for most structural/hidden elements are perfectly fine. For visible exterior elements on a display MOC, new parts are worth the premium.
• Check seller ratings and feedback. BrickLink has a robust feedback system. Sellers with thousands of positive reviews and high accuracy ratings are worth the slightly higher prices. A wrong part shipped to you costs more in time and reorder fees than the few cents you saved.
• Order in bulk from one seller when possible. Many sellers offer quantity discounts. If you need 200 white 1x2 bricks, buying them all from one seller is almost always cheaper than splitting across multiple stores.

Stud.io by BrickLink

Stud.io is BrickLink's free digital LEGO design software, and for MOC builders it has become the industry standard. It runs on Windows and Mac, uses real BrickLink part numbers for every element, and features a direct pipeline from digital design to BrickLink parts ordering. What you design, you can buy — part for part, color for color.

Why Stud.io Matters for MOC Builders

Before Stud.io, most MOC builders designed either in LEGO Digital Designer (LDD, now discontinued), LDraw-based tools (powerful but steep learning curve), or simply by trial-and-error with physical bricks. Stud.io changed the workflow fundamentally. You can now design an entire model digitally, verify that every part exists and is available for purchase, generate photorealistic renders of the finished build, and export a complete parts list with BrickLink catalog links — all before spending a single dollar on bricks.

The software includes a built-in rendering engine that produces publication-quality images of your designs. For builders who want to share their work online, create building instructions for others, or simply visualize what a model will look like before committing to a parts order, this is transformative. The renders aren't just previews — they're genuinely impressive images that rival professional LEGO photography.

Stud.io also includes a stability checking tool that analyzes your model's structural integrity. It identifies elements that aren't properly connected, joints that would be too weak to support the weight above them, and sections that would collapse in a physical build. For large MOCs — especially tall structures like the IMS Pagoda — this feature catches structural problems that would be expensive to discover only after ordering parts.

Learning Stud.io

I learned Stud.io from scratch for the IMS Pagoda project with zero prior experience in digital LEGO design. The full learning journey — what worked, what didn't, the shortcuts that save hours, and the pitfalls that waste them — is documented in IMS Pagoda Part 7: Learning Stud.io. If you're picking up the software for the first time, that article is the practical guide I wish I'd had when I started.

The short version: Stud.io has a moderate learning curve. The interface is intuitive for basic brick placement, but advanced features — hinge connections, flexible parts, collision detection settings, and the rendering pipeline — take time to master. Plan on a weekend of focused exploration before you're comfortable designing at speed.

Key Parts Referenced on This Site

Across the builds and reviews on The Earl of Bricks, certain parts come up repeatedly. They're the workhorses — the elements that solve specific design problems, define architectural details, or form the structural backbone of large MOCs. Here's a reference table of the most notable ones:

This table will grow as more builds and reviews are published. Each part listed here is one I've used in a real project or discussed in a review — not theoretical picks from a catalog, but parts that have proven their value in actual builds.

The floor plate rule for the IMS Pagoda: largest plates on the perimeter, smallest toward the center. Always 6×16 plus 6×8 combinations — never 6×24 plates, which are cost-prohibitive at the quantities this build demands.

Bulk Buying: When and How

BrickLink is the precision tool — you buy exactly what you need, part by part, color by color. But for large MOCs that require hundreds or thousands of common bricks in basic colors, buying specific parts at retail prices adds up fast. That's where bulk buying enters the picture.

BrickLink for Specific Parts

Use BrickLink when you need exact part numbers in exact colors. Specialty slopes, specific window elements, rare colors, printed tiles, minifigure accessories — these are BrickLink purchases. The premium you pay per part is justified by the certainty that you're getting exactly what your design requires. There is no substitute for BrickLink when color accuracy and part specificity matter.

Facebook Marketplace for Bulk Lots

For common bricks in high quantities — white 2x4s, light bluish gray plates, black tiles — Facebook Marketplace bulk lots are often the most cost-effective source. Sellers list bags, bins, and tubs of unsorted LEGO by weight, typically at $5–$15 per pound depending on your market. The tradeoff: you get a random assortment. You'll need to sort everything yourself, and most of what you receive won't be what you need.

But the economics can work in your favor. If you need 300 white bricks and they cost $0.10 each on BrickLink ($30 plus shipping from multiple sellers), but a 10-pound bulk lot costs $60 and contains 400+ white bricks plus thousands of other useful pieces, the bulk lot wins — and you end up with a massive general inventory for future builds.

The full story of my first bulk buy — the thrill, the haul, and the deeply therapeutic process of sorting through thousands of unknown bricks — is in IMS Pagoda Part 8: The Bulk Buy. If you've never bought bulk LEGO before, that article covers what to look for, what to avoid, and how to sort efficiently.

The Decision Framework

Here's the simple rule:

• Specific parts, specific colors, small quantities → BrickLink. Pay the premium for precision.
• Common bricks, basic colors, large quantities → Bulk lots (Facebook Marketplace, garage sales, estate sales). Pay by weight, sort yourself.
• Complete sets for part harvesting → Sometimes buying an entire retired set is cheaper than buying its parts individually on BrickLink. Check the math before assuming BrickLink is always cheapest.

Most serious MOC builders use all three channels. BrickLink is the backbone. Bulk buying fills the common-part inventory. And occasionally, a retired set on clearance or at a garage sale provides a windfall of useful elements at a fraction of BrickLink prices.

Building Your Parts Inventory

As you take on more MOC projects, you'll naturally accumulate a parts inventory. The question is whether you manage it intentionally or let it become an unsorted mountain of plastic. Intentional inventory management is one of the biggest time-savers in MOC building.

Sort by part type first, then by color. All 2x4 bricks together, subdivided by color. All 1x2 plates together, subdivided by color. This mirrors how BrickLink catalogs parts and how Stud.io organizes its palette. When you're mid-build and need a Dark Bluish Gray 1x4 tile, you should be able to reach for it in under 10 seconds. If you're digging through an unsorted bin, you'll spend more time searching than building.

Label storage with BrickLink part numbers. It sounds obsessive. It is obsessive. It also means that when you pull up a parts list from a Stud.io design, you can walk directly to the correct drawer and grab what you need. The overhead of labeling pays for itself on the first large build.

Track what you own. BrickLink allows you to maintain a personal inventory — a catalog of every part you own, by part number, color, and quantity. Keeping this updated means you can cross-reference any future MOC design against your existing stock before placing a parts order. You'd be surprised how often you already own 60–70% of what a new build requires. The remaining 30–40% is all you need to buy.

This level of organization isn't required for casual building. But if you're designing museum-quality MOCs with thousands of parts — like the IMS Pagoda detail work — disciplined parts management is the difference between a project that moves forward and one that stalls because you can't find the 47 Light Bluish Gray 1x2 bricks you know you own somewhere in the house.