Skip to content
Back of the Box Builds

Back of the Box Builds

LEGO Alternate Builds!

  • SETS
    • Adventurers
    • Aquazone
    • Belville
    • BATMAN™
    • BIONICLE
    • Building Set with People
    • Castle
    • Duplo
    • Fabuland
    • Harry Potter
    • Holiday and Event
    • LEGOLAND
    • Model Team
    • Pirates
    • Space
    • Star Wars
    • Technic
    • Train
    • Town
    • Universal Building Set
    • Western
    • More Sets
    • Misc
  • USEFUL LINKS
    • Submit Instructions!
    • New Instructions
    • New Official Sets
    • New Alternate Builds
    • Minifigs
    • Very Small Builds
    • Small Builds
    • Medium Builds
    • Large Builds
    • Extra Large Builds
    • How BOTBB was Built
  • THIS IS AN INDEPENDENT SITE NOT AUTHORIZED OR SPONSORED BY THE LEGO GROUP
Alternate Builds Instructions Added Large Alt Build Large Builds Model Team Model Team Alternate Builds 

5521 – Back A

January 29, 2026March 4, 2026 Master Builder 4649 Views

From: 5521: Sea Jet
Name: TBD 1
Instructions: View PDF | Download .io File

Contributions

  1. Name, PDF and .io file submitted on January 29, 2026 by: livi
  • ← Space Skeletal Horse Concept
  • 5581 – Back A →

You May Also Like

6940 – Inside B

March 29, 2023March 30, 2023 Master Builder

Book 260 – Page 46-47

February 5, 2023February 13, 2023 Master Builder

6801 – Back C

September 22, 2019October 25, 2021 Master Builder

735 – Back B

September 15, 2022September 15, 2022 Master Builder

6959 – Back B

April 27, 2020April 27, 2020 Master Builder

6335 – Back D

December 22, 2023January 1, 2024 Master Builder

EXPLORE MORE OFFICIAL SETS

1966: Car Repair Shop
Classic Town Large Builds Official Sets Town Town Sets Traffic 

1966: Car Repair Shop

May 16, 2025May 16, 2025 Master Builder

Year Released: 1985BricklinkInstructions

4557: Freight Loading Station
9V Medium Builds Official Sets Town Train Train Sets 

4557: Freight Loading Station

July 10, 2026July 10, 2026 Master Builder
6932: Stardefender 200
ABCs Futron Sets Futuron Large Builds Official Sets Space 

6932: Stardefender 200

September 24, 2019August 15, 2023 Master Builder
924 (487): Space Cruiser
Classic Space Classic Space Sets Different Box Versions Different Set Numbers Jens Nygaard Knudsen LL Link Medium Builds Official Sets Space 

924 (487): Space Cruiser

January 25, 2022October 17, 2024 Master Builder
3676: Catherine Cat’s Fun Park
Box Story Fabuland Fabuland Sets Official Sets Small Builds 

3676: Catherine Cat’s Fun Park

March 1, 2025March 1, 2025 Master Builder
1680: Hay Cart with Smugglers
Castle Castle Sets Forestmen Official Sets Small Builds 

1680: Hay Cart with Smugglers

August 12, 2024September 24, 2024 Master Builder
4733: The Dueling Club
Chamber of Secrets Harry Potter Harry Potter Sets Medium Builds Official Sets 

4733: The Dueling Club

March 3, 2023March 3, 2023 Master Builder
6709: Tribal Chief
Indians Official Sets Very Small Builds Western Western Sets 

6709: Tribal Chief

October 10, 2023October 10, 2023 Master Builder
730: Steam Shovel with Carrier
Construction LEGOLAND Medium Builds Official Sets 

730: Steam Shovel with Carrier

February 21, 2024February 21, 2024 Master Builder
1371: Spinosaurus Attack Studio
Jurassic Park III Medium Builds Official Sets Studio Alternate Builds Studio Sets Studios 

1371: Spinosaurus Attack Studio

January 6, 2022June 4, 2024 Master Builder
1818: Aircraft and Ground Support Equipment and Vehicle
Airport Classic Town Medium Builds Official Sets Town Town Sets 

1818: Aircraft and Ground Support Equipment and Vehicle

April 7, 2025April 7, 2025 Master Builder
6493: Flying Time Vessel
Large Builds Official Sets Time Cruisers Time Cruisers Sets 

6493: Flying Time Vessel

July 14, 2021December 29, 2021 Master Builder
1843 – Side R
Bonus/Value Pack Alternate Builds Castle Castle Alternate Builds Instructions Added Official Sets Royal Knights Small Alt Build Small Builds Space Spyrius Spyrius Alternate Builds 

1843 – Side R

January 22, 2021March 14, 2025 Master Builder
6263: Imperial Outpost
Imperial Guards Medium Builds Official Sets Pirates Pirates I Pirates Sets 

6263: Imperial Outpost

February 21, 2025February 21, 2025 Master Builder
6761: Bandit’s Secret Hide-Out
Box Story Cowboys Jørn Thomsen Large Builds Official Sets Western Western Sets 

6761: Bandit’s Secret Hide-Out

December 29, 2021April 3, 2024 Master Builder
6441: Deep Reef Refuge
Divers Large Builds Official Sets Town Town Sets 

6441: Deep Reef Refuge

November 6, 2019December 29, 2021 Master Builder

BOXES

INSTRUCTIONS

FAVORITES

MINIFIGS

About This Site

Logo
There were once pictures of additional LEGO® builds on the back of set boxes. Written on the boxes was typically something about the endless building possibilities, "Build any of these exciting models with this set!" There were no instructions for these alternate builds, until now.

Sets

  • Adventurers
  • Aquazone
  • BATMAN
  • Bionicle
  • Belville
  • Building Set with People
  • Castle
  • Duplo
  • Fabuland
  • Harry Potter
  • Holiday and Event
  • LEGOLAND
  • Model Team
  • Pirates
  • Space
  • Star Wars
  • Technic
  • Train
  • Town
  • Universal Building Set
  • Western
  • More Sets
  • Misc

Useful Links

  • Submit Instructions!
  • New Instructions
  • New Official Sets
  • New Alternate Builds
  • Minifigs
  • Very Small Builds (<35 pcs)
  • Small Builds (<100 pcs)
  • Medium Builds (<200 pcs)
  • Large Builds (<400 pcs)
  • Extra Large Builds (>400 pcs)
  • How BOTBB was Built

In Honor of 1526

The classic space set that never was.

Copyright © 2026 Back of the Box Builds. All rights reserved. LEGO® is a trademark of the LEGO Group of companies which does not sponsor, authorize, or endorse this site.