How Machines Build 3D Objects Layer by Layer from Melting Plastic
This patent describes a method and machine for creating three-dimensional objects by precisely depositing melted material, layer by layer, from a movable nozzle onto a base.
Original patent title: “Apparatus and method for creating three-dimensional objects”
This patent describes a method and machine for creating three-dimensional objects by precisely depositing melted material, layer by layer, from a movable nozzle onto a base. Granted to Stratasys Inc in 1992 with 50 claims and 793 forward citations, and it is now in the public domain.
Key facts
Coverage
What does this patent actually cover?
This patent describes an apparatus that builds a three-dimensional object by sequentially depositing multiple layers of solidifying material. It uses a movable head with a dispensing outlet, or nozzle, that releases material in a fluid state, such as melted plastic (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1). This material then solidifies at a specific temperature. A mechanical system moves the dispensing head and a base member relative to each other along X, Y, and Z axes (Claim 1). This movement allows the machine to precisely place each layer, building up the object slice by slice. For example, a computer-aided design (CAD) program can create a 3D model, which is then converted into instructions for the machine to deposit material for each layer (Claim 11).
The gap
What does this patent NOT cover?
- Does not cover 3D printing methods that do not involve depositing material from a dispensing head, such as laser sintering of powder or stereolithography using light to cure liquid resin.
- Does not cover processes where the material does not solidify after being discharged from the nozzle, as ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1 specifies a 'supply of material which solidifies at a predetermined temperature'.
- Does not cover methods that build objects without forming 'multiple layers' sequentially, as described in ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1.
- Does not cover systems where the dispensing head and base member do not move relative to each other in three dimensions along 'X,' 'Y,' and 'Z' axes.
- Does not cover 3D printing techniques that do not meter the discharge of material from an orifice at a predetermined rate, as required by ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The core innovation was precisely controlling the deposition of a material that changes state (from fluid to solid) in successive, thin layers. By moving a dispensing head and base member in three dimensions, and carefully metering the material, complex shapes could be built up automatically, layer by layer, with controlled thickness.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Stratasys FDM 3D printers
Ultimaker desktop 3D printers
Prusa Research 3D printers
Creality Ender series 3D printers
Most consumer-grade 3D printers that use plastic filament
Why it matters
The bigger picture
This patent is foundational to Fused Deposition Modeling (FDM), one of the most widely used 3D printing technologies today. It laid the groundwork for how many modern 3D printers operate, enabling the creation of physical prototypes and functional parts directly from digital designs. The company Stratasys, founded by the inventorinventorThe person who actually conceived the invention. Listed on the patent regardless of who owns it.Read more →, commercialized this technology, making 3D printing accessible for various industrial and, eventually, consumer applications.
Filed
October 30, 1989
Granted
June 9, 1992
Market context
Who's building on this
Companies in this space
Stratasys Inc., the original assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →, continues to be a major player in the additive manufacturing space, developing and selling advanced FDM systems for industrial use. Other companies like Ultimaker, Prusa Research, and Creality have built upon similar principles to create a vast market for desktop and prosumer FDM 3D printers, making the technology widely accessible.
Market impact
This patent, and the technology it describes, created the Fused Deposition Modeling (FDM) segment of the 3D printing market. It enabled the rapid prototyping industry to flourish by offering a relatively affordable and accessible way to produce physical models directly from CAD files. This technology became a cornerstone for product development across many industries and eventually paved the way for the widespread adoption of desktop 3D printers, significantly impacting manufacturing and design processes globally.
Claim 1 — Plain English
What this patent covers
This patent describes an apparatus that builds a three-dimensional object by sequentially depositing multiple layers of solidifying material. It uses a movable head with a dispensing outlet, or nozzle, that releases material in a fluid state, such as melted plastic (Claim 1). This material then solidifies at a specific temperature. A mechanical system moves the dispensing head and a base member relative to each other along X, Y, and Z axes (Claim 1). This movement allows the machine to precisely place each layer, building up the object slice by slice. For example, a computer-aided design (CAD) program can create a 3D model, which is then converted into instructions for the machine to deposit material for each layer (Claim 11).
The clever bit
The core innovation was precisely controlling the deposition of a material that changes state (from fluid to solid) in successive, thin layers. By moving a dispensing head and base member in three dimensions, and carefully metering the material, complex shapes could be built up automatically, layer by layer, with controlled thickness.
What it does not cover
- Does not cover 3D printing methods that do not involve depositing material from a dispensing head, such as laser sintering of powder or stereolithography using light to cure liquid resin.
- Does not cover processes where the material does not solidify after being discharged from the nozzle, as Claim 1 specifies a 'supply of material which solidifies at a predetermined temperature'.
- Does not cover methods that build objects without forming 'multiple layers' sequentially, as described in Claim 1.
- Does not cover systems where the dispensing head and base member do not move relative to each other in three dimensions along 'X,' 'Y,' and 'Z' axes.
- Does not cover 3D printing techniques that do not meter the discharge of material from an orifice at a predetermined rate, as required by Claim 1.
Patent Journey
From filing to expiry
PatentBrief Score
Impact Score
Strong
Citation count
40/40
Highly cited
Claim breadth
20/20
Very broad protection
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$115K – $369K
Midpoint $230K · expired or expiring · industry ×1.6
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
50 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Crump, S. S. (1992). How Machines Build 3D Objects Layer by Layer from Melting Plastic (U.S. Patent No. 5,121,329). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/5121329/fdm-3d-printing-stratasys
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Machines Build 3D Objects Layer by Layer from Melting Plastic cover?
This patent describes a method and machine for creating three-dimensional objects by precisely depositing melted material, layer by layer, from a movable nozzle onto a base.
Who owns patent US 5121329?
Stratasys Inc owns this patent, granted in 1992.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 5121329 cited by?
This patent has been cited by 793 later patents that build on its ideas.
What problem does this patent solve?
This patent is foundational to Fused Deposition Modeling (FDM), one of the most widely used 3D printing technologies today. It laid the groundwork for how many modern 3D printers operate, enabling the creation of physical prototypes and functional parts directly from digital designs. The company Stratasys, founded by the inventor, commercialized this technology, making 3D printing accessible for various industrial and, eventually, consumer applications.
What does this patent NOT cover?
Does not cover 3D printing methods that do not involve depositing material from a dispensing head, such as laser sintering of powder or stereolithography using light to cure liquid resin.
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