LEGO files its stud-and-tube brick patent in Denmark
On 28 January 1958, the LEGO Group filed a Danish patent application for an improved building element. Tubes inside the hollow brick strengthened its grip on other bricks while preserving the ability to pull a construction apart and rebuild it.
A problem hidden underneath
LEGO’s plastic construction toys depended on more than attractive shapes and colors. A model needed enough grip to stay together during play, yet its pieces had to separate without damage. Earlier hollow bricks did not provide the stability the company wanted, and customer complaints made improvement urgent. Godtfred Kirk Christiansen’s work therefore focused on the connection between pieces. The important innovation could be overlooked from above: it lay within the underside of an otherwise familiar-looking studded brick.
The application of 28 January
The company’s historical account records the Danish application on 28 January 1958 at 1:58 p.m. It followed a discussion of possible solutions a few days earlier. Filing an application was a specific legal step, distinct from inventing the concept, manufacturing every later version, or receiving grants in other countries. Surviving patent records make these distinctions visible. The related United States patent claims priority from the Danish filing but has its own later application and publication dates.
How the connection works
Inside the brick, projecting tubes create additional contact surfaces. When another brick’s studs enter the open underside, they fit between the interior structures and outer walls. The resulting clamping action improves stability. The patent describes this relationship in terms of projections and points of contact, allowing different relative arrangements of the blocks. The usefulness lies in the balance: the connection holds, but the user can deliberately undo it. A successful construction toy needs both of those properties, rather than maximum permanent strength.
A system that invites rebuilding
This small geometric change supported the idea of a building system in which pieces could participate in many constructions. The invention was not simply a miniature house or vehicle; it improved the reusable relationship between components. Patent filings in different countries also show how an everyday toy became an internationally protected product. The accompanying illustration uses unbranded bricks to evoke a period workshop. It is an imagined scene, not evidence of the precise desk, prototype colors or hand movements involved in the filing.
Wonderful Copenhagen - 155 Waltz - Mastered
Tim Laskey
Laskey's later keyboard arrangement of the song about Copenhagen supplies Danish cultural context for the Billund invention. This skating waltz recording is not associated with the patent filing itself.
Listen on SoundCloud ↗Follow the evidence.
- LEGO History: The stud and tube principle ↗
- US3005282A: Toy building brick patent ↗
- Brickset: Original LEGO patent scans ↗
- Tim Laskey: Wonderful Copenhagen, 155 Waltz ↗
AI-assisted writing, with institutional and primary sources. Illustration is a reconstruction, not an archival photograph. Published October 31, 2026; updated October 31, 2026. Our approach
