Custom LEGO MOC instructions work differently from official LEGO sets. When you buy instructions on Rebrickable, you get a PDF building guide and a complete parts list. You then source the parts yourself, either from your own collection or by ordering through BrickLink, the largest marketplace for buying and selling individual LEGO pieces, and owned by the LEGO Group.

This guide walks through the full process, including a step that lets you check part availability and estimated cost before you spend a dollar.

What You Need Before You Start

• A free Rebrickable account — required to purchase instructions and access the parts export tool
• A free BrickLink account — required to order parts

Both are free to create. Set those up first, then come back here.

Step 1: Check the Parts Inventory Before You Buy

One of the most useful things about Rebrickable is that you can browse the parts inventory for any MOC before purchasing instructions. This lets you estimate cost and see whether any parts might be difficult to source. 

On any Rebrickable MOC page, click the Inventory tab. You’ll see the total part count, a rough current cost estimate, and a visual list of every piece in the build. Note that large inventories require you to be signed in with a Rebrickable account to view.

Take a look before committing. If a build is 748 parts and most of them show as common and inexpensive, you can move forward with confidence.

Step 2: Purchase and Download the Instructions

When you’re ready, purchase the instructions on Rebrickable. After checkout, download the PDF. This is your building guide. 

Keep the Rebrickable MOC page open in a tab, you’ll come back to it in a later step.

Step 3: Export the Parts List to BrickLink

From the Rebrickable MOC page, click the Add Parts to BrickLink Wanted List button. 

If you get an error, your browser is likely blocking the pop-up. Click the icon in your browser’s URL bar to allow pop-ups from Rebrickable, then try again. 

In the pop-up window, select New Wanted List, name it after the MOC, scroll down, and click Add Parts. When the button changes to View Wanted List, click it. 

A new BrickLink window will open with your complete wanted list.

Step 4: Remove Parts You Already Own

Before ordering, go through the list and remove or reduce quantities for any parts you already have in your collection. 

To remove a part entirely, check the box for that row and click the delete icon at the top of the screen. 

To update a quantity, click into the quantity field for that row, adjust the number, and click Save Changes at the bottom of the screen. 

If you want to check for common parts through LEGO’s own store, Pick-a-Brick carries current production pieces in standard colors. It’s worth checking for basic bricks and plates, but it won’t have specialty parts, discontinued pieces, or many of the SNOT elements that MOC builds rely on. BrickLink will cover everything else.

Step 5: Set Part Condition

Decide whether you want new or used parts. If you prefer new, you need to set this manually. BrickLink only applies condition changes to parts visible on the current page, so this takes a few repetitive steps for larger builds. 

First, change the view from the default 25 parts per page to 100 using the dropdown at the top of the list. 

Then, starting on page 1, click the checkbox in the table header to select all rows, click the Condition button, select New or Used, and click Apply. Repeat for each remaining page.

Step 6: Find Stores and Place Your Order

Click Buy All. 

Use the filters to narrow down stores. If you’re in the US, the USA filter keeps shipping faster and cheaper. Checking Instant Checkout lets you pay immediately rather than waiting for a manual invoice from the seller. 

Click Auto-select and BrickLink will identify the combination of stores needed to cover your full parts list.

Before you create carts, do two quick checks: 

Check shipping costs. You pay separate shipping to each store. The auto-select tool optimizes for fewest stores, but it’s worth reviewing before proceeding. 

Check for rare parts.Compare the unique lot count BrickLink shows against the total part count on the Rebrickable inventory tab, which should still be open in another tab. If the numbers don’t line up, BrickLink may not have found every part, often because one piece is rare or unavailable in your region. You don’t want to order everything and find out later you’re missing a single key piece. 

Once you’re satisfied, click Create Carts, then work through each store’s checkout. Before completing each order, it’s worth clicking into the store directly to see if they carry anything else you’ve been looking for. Since you’re already paying for shipping, it’s a good opportunity to pick up other pieces at no extra shipping cost.

A Note on Part Costs

The cost estimate on Rebrickable’s inventory tab is a rough ballpark based on current BrickLink market prices. Your actual cost will vary depending on which stores you buy from, condition (new vs. used), and shipping.

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