Missing Piece Checker: 42105 Catamaran

Checking

42105 Catamaran

405 pieces in 76 part and color combinations.

LEGO counts 404 pieces. This inventory comes from a separate parts catalog and lists 405; 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. This set comes with 8 spare pieces, marked on each row of the checklist. One may be the piece you need.
The floor and your building area. Check under furniture, the chair and the edges of your building surface.

Piece checklist

Technic Pins 134 pieces

Technic Pin with Friction Ridges Lengthwise and Center Slots Black Part 2780 Element 4121715 or 278026 1 spare in the box ×47
Technic Pin with Friction Ridges Lengthwise and Towball Black Part 6628 Element 4184169 or 662826 ×14
Technic Axle Pin with Friction Ridges Lengthwise Blue Part 43093 Element 4309323 or 4206482 ×33
Technic Pin Long with Friction Ridges Lengthwise, 2 Center Slots Blue Part 6558 Element 4514553 ×17
Technic Axle Towball Light Bluish Gray Part 2736 Element 6443149 or 4211375 ×3
Technic Pin 1/2 without Friction Ridges Light Bluish Gray Part 4274 Element 4274194 or 4211483 1 spare in the box ×9
Technic Pin Long with Friction Ridges Lengthwise and Stop Bush [3 Lateral Holes, Big Pin Hole] Light Bluish Gray Part 32054 Element 4211865 ×8
Technic Axle Pin 3L with Friction Ridges Lengthwise and 1L Axle Red Part 11214 Element 6209519 ×2
Technic Axle Pin without Friction Ridges Lengthwise Tan Part 3749 Element 4666579 or 4186017 ×1

Technic Bushes 13 pieces

Technic Bush Light Bluish Gray Part 3713 Element 6275844 or 6271817 1 spare in the box ×8
Technic Bush 1/2 Smooth with Axle Hole Semi-Reduced Light Bluish Gray Part 32123b Element 6271165 or 4211573 1 spare in the box ×5

Technic Panels 10 pieces

Technic Panel Fairing #21 5L Small Smooth, Side B Black Part 11946 Element 6316923 or 6023036 ×3
Technic Panel Fairing #22 5L Small Smooth, Side A Black Part 11947 Element 6319983 or 6022761 ×3
Technic Panel Fairing #21 5L Small Smooth, Side B Lime Part 11946 Element 6340657 or 6218483 ×2
Technic Panel Fairing #22 5L Small Smooth, Side A Lime Part 11947 Element 6352667 or 6218484 ×2

Technic Gears 9 pieces

Technic Gear 12 Tooth Double Bevel Black Part 32270 Element 4177431 ×3
Technic Gear Rack 1 x 13 with Axle and Pin Holes Black Part 64781 Element 6302830 or 4540906 ×2
Technic Worm Gear Short Dark Bluish Gray Part 27938 Element 6170153 ×2
Technic Gear 20 Tooth Double Bevel with Axle Hole Type 1 [+ Opening] Tan Part 18575 Element 6346517 or 6084724 ×2

Technic Beams Special 6 pieces

Technic Beam 3 x 0.5 Liftarm with Boss and Pin Semi-Reduced Black Part 33299b Element 4563044 ×5
Technic Beam 5 x 11 with 3 x 5 Opening Frame Thick Light Bluish Gray Part 64178 Element 4540797 ×1

Technic Special 4 pieces

Technic Rotor Blade Small with Hole and Axle Connector End Dark Bluish Gray Part 99012 Element 6271639 or 4651820 ×4

Technic Steering, Suspension and Engine 4 pieces

Technic Link 1 x 9 Black Part 32293 Element 6244698 or 4141300 ×4

Transportation - Sea and Air 4 pieces

Boat / Pontoon 36 x 7 x 7 with Blue Bottom Lime Part 65781 Element 6285651 ×2
Sail, Triangular, with 'Kool Keels Anchor Bouy', '42105', and Waves with Dots Print [No Color/Any Color] Part 66645a ×1
Sail, Triangular, with Waves with Dots Print [No Color/Any Color] Part 66645b ×1

Plates Round Curved and Dishes 3 pieces

Plate Round 1 x 1 with Solid Stud Trans-Clear Part 6141 Element 6514052 or 6240030 1 spare in the box ×1
Plate Round 1 x 1 with Solid Stud Trans-Green Part 6141 Element 6514057 or 6240221 1 spare in the box ×1
Plate Round 1 x 1 with Solid Stud Trans-Red Part 6141 Element 6514051 or 6208450 1 spare in the box ×1

Transportation - Land 2 pieces

Steering Wheel Small, 2 x 2 [Reinforced] Black Part 16091 Element 6057397 ×2

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

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.

LEGO Missing Piece Checker

42105 Catamaran

Before you call it missing

Your missing list