You can freely build on How the Modern LEGO Brick Design Works
This patent expired in 1978. Every claim — 0 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
Interlego AG
Patent granted
1961
Expired
1978
Forward citations
374
What this patent covers
This patent describes the structural design of a toy building brick that features hollow cylindrical tubes on its underside. These tubes are positioned to frictionally engage the walls of other bricks when pressed together. This specific arrangement allows for a stable, interlocking connection that remains secure even when the structure is moved or turned upside down. It transformed simple plastic blocks into a versatile construction system.
What is now free to use
All 0 claims of US 3005282 are in the public domain. Specifically:
The 0 dependent claims add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
Does not cover bricks without the specific hollow tube configuration on the underside
Does not cover non-plastic materials or different geometric shapes like spheres or pyramids
Does not cover the specific chemical composition of the plastic used
Who is building on this today
The LEGO Group remains the primary developer of this system, continuously refining the tolerances and material science of the bricks. Many compatible 'brick-compatible' toy manufacturers have emerged since the original patent expired, building on this fundamental geometry.
Products built on expired version of this technology
Standard 2x4 LEGO bricks
LEGO Technic beams
LEGO Duplo blocks
How to cite this patent in your documentation
Interlego AG. US Patent 3005282. Toy building brick. Granted 1961, expired 1978. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.