Free tool

LEGO Missing Piece Checker

Rule out the usual hiding places first. If the piece really is gone, check the set piece by piece and leave with the element ID LEGO asks for, or a link to buy the part.

Checking

66642 Ultimate Designer Kit

2 pieces in 2 part and color combinations.

LEGO counts 388 pieces. This inventory comes from a separate parts catalog and lists 2; the two do not always count the same elements, so their totals differ. Spare parts are counted in neither figure.

Before you call it missing

Builders who report a missing piece often find it in one of these places. Tick each one off as you look.

Every bag and the box. Shake out each bag, check its corners and seams, and look inside the empty box.
Inside what you have built. Small pieces lodge inside tubes, under plates and between studs. Turn the model over and look.
The last few steps. Compare each recent step with its parts callout. A piece used in the wrong place earlier leaves you one short later.
Look-alike colors. Compare each color with the step's parts callout, especially White against Trans-Clear.
The spare pieces. Many sets include a few extra small pieces. Check them before you order a replacement.
The floor and your building area. Check under furniture, the chair and the edges of your building surface.

Piece checklist

Medium Azure 1 piece

Sorting Tray, DOTS, 7 Compartment Medium Azure Part 901957 ×1

Trans-Clear 1 piece

Sorting Tray, DOTS, Lid Trans-Clear Part 901956 ×1

Tick each piece as you find it, or mark it missing.

Sets inside this set

This set packs other sets whose pieces are listed separately. Check each one:

When a piece really is missing

Ask LEGO

LEGO takes requests for pieces missing from a new set through its customer service site. The form asks for the set number and each piece's element ID, the number printed beside the piece in the parts list at the back of the instructions. This checker lists both.

Request a replacement from LEGO

Buy the piece

Mark a piece missing and your list links it to an eBay search for that part, which also covers pieces from older or second-hand sets.

Keep a record

Copy or download your missing list (the CSV opens in any spreadsheet), or print the whole checklist and tick pieces off on paper. Your marks stay in this browser, so you can check a big set over several sittings.