How to Find Parts for a MOC: BOM to Checkout Guide

You download a MOC plan you love, sit down ready to build, and then it hits you: half the parts are unfamiliar, you have no idea where to buy them, and you have even less idea what the whole thing will cost. Almost every new builder gets stuck at exactly this point. This guide walks the full chain, from reading the parts list to placing the final order, so you can gather everything a MOC needs without wasting money or weeks of back-and-forth shipping.

Step 1: Read the Parts List (BOM)

Nearly every well-made MOC plan ships with a Bill of Materials (BOM). A proper BOM is not a casual list of names. Each line contains a part number (a numeric ID like 3001 or 3023), a color, a quantity, and sometimes a reference photo of the actual piece.

Before you buy anything, spend ten minutes actually reading that list:

• Search by number, not by name. Each number maps to one fixed specification. Part numbers are far more reliable than names, because the same piece can be called completely different things across brands and catalogs.
• Separate official color names from nicknames. Official color IDs and casual names (light gray, blue-gray and so on) are easy to mix up. Trust the code or color swatch shown in the ordering interface.
• Total up colors and quantities first. Work out how many pieces you need per color before planning the purchase. This dramatically cuts the number of separate orders and spreads shipping cost across fewer transactions.

If the plan has no BOM, free parts-management software can scan the plan or let you enter pieces manually and generate a numbered list for you. That generated list is the foundation everything else sits on.

Step 2: Look Up Parts by Number and Pick a Buying Channel

Once the numbers make sense, the question shifts from "how do I find parts for a MOC" to "where do I buy them, and how." There are three broad channels, each with trade-offs:

• General e-commerce platforms. Search the part number and order directly. Plenty of sellers, easy price comparison, and a good fit for topping up a small shortfall. The downside is that per-piece prices usually run high, so filling a large list this way gets expensive fast.
• Specialist brick parts stores and bulk-parts sites. Search by number in bulk, with stock deducted automatically, and import a whole BOM to build a cart in one click. For assembling an entire MOC list, this is currently the least painful route. Watch the price differences between stores and any free-shipping thresholds.
• Third-party compatible brands. Many Chinese brick brands sell individual parts packs at friendly prices, and their precision has improved noticeably in recent years. This suits budget-conscious builders or anyone massing up scenery. If feel and tolerance matter to you, though, use original or well-reviewed compatible makers for the main structural pieces.

A practical rule: buy in bulk from parts stores, plug small gaps with e-commerce orders. Pricing the entire list at once before you order saves far more than buying one piece here and one piece there.

Step 3: Substitutions and Cost Estimation

Even with a clean BOM order, you will eventually hit discontinued pieces, a color that is out of stock, or parts you already own. That is when substitutions come in:

• Same spec, different color. Swapping color on structural pieces barely affects the build, and it lets you tweak the color scheme while you are at it. This is the most common beginner move.
• Different part, same function. Two thin plates instead of one thick brick, or a compatible part instead of an original one. Just verify the dimensions match.
• Simplified structure. Non-load-bearing decorative sections can be simplified or skipped. Protect the load-bearing and clutch-critical structure first.

Do not guess at cost. Multiply each BOM line's quantity by its unit price, add them all up, then add shipping and an allowance for loss. Bulk parts orders almost always include a few damaged or missing pieces, so budget roughly 5% extra per color. Buying everything in one pass is generally cheaper than repeated top-up orders. The realistic expectation is that value comes from channel choice and batching, not from haggling over individual pieces.

Beginner Pitfall Checklist

Here is a practical list to check before you hit buy:

1. Never buy by name alone. Confirm the part number and the reference photo before ordering, or you risk getting the wrong specification.
2. Do not ignore compatibility. Tolerance differences between third-party brands, and between third-party and original parts, can affect clutch. This matters especially on large builds.
3. Do not buy mixed-color "blind box" parts lots. They are fun, but useless for filling a precise list.
4. Place a small trial order first. Confirm a store's quality control and shipping speed before committing to a bulk purchase.
5. Keep a digital copy of the list. It makes future MOC modifications and reorders much easier to reuse.

Final Notes

Missing parts is the hurdle that turns away more new builders than anything else, and it is also the least important one. Learn to read a BOM, trust part numbers over names, and choose the right channel, and finding parts becomes a matter of time rather than luck. If you want MOC plans that come with complete parts lists and are ready to build, BrickPlans (https://brickplan.cn) covers the whole path from picking a plan to sourcing the pieces.

Written by the BrickPlans team. Please credit the source when republishing.