Shredder 3.3 build gallery photograph · Precious Plastic / One ArmySource ↗

Image credits and source versions

Shredder small 3.3 with collection bins and transport trolley ↗ · Precious Plastic Headquarters · CC BY-SA 4.0
Shredder small 3.3 hopper, motor and control enclosure ↗ · Precious Plastic Headquarters · CC BY-SA 4.0

CAIBI ASSESSMENT

Precious Plastic Shredder 3.3

CAIBI VERDICTBUILD FOR THE EXPERIENCE

An open-source workshop machine that reduces sorted plastic waste into flakes for later recycling processes, with downloadable fabrication files and a documented safety-focused 3.3 revision.

See what the build involves Original source ↗

Build or buy?

Compare the documented build with the purchase reference.

Build it yourself

Build estimate£650–£1,370CAIBI estimate · medium confidenceParts and local fabrication allowance; equipped workshop required

Time: 1-2 weeks is the current source estimate for the Shredder small 3.3 build. That assumes access to, or subcontracting of, the required metalworking, machining and electrical work.
Difficulty: 5/5
Physical processes: Grinder · Chop saw · MIG/MAG or TIG welder · Drill press · Lathe · Laser-cutting service or suitable metal-cutting equipment · Torque wrench · Bearing mounting tools · Electrical test equipment

See build requirements →

Purchase reference

Buy price referencePrice not checkedNo priced alternative recorded

Check the source for the exact model, availability and what is included.

Check comparison evidence →

Purchase comparison not yet priced

What the prices cover

Planning range for laser-cut steel, geared motor/drive, shaft/bearings, guarding and electrical hardware. Precious Plastic publishes the full BOM but not a stable global all-in 3.3 price; current comparable build estimates vary substantially by local fabrication.

Includes: Steel knife/frame fabrication; Geared motor/drive; Shaft/bearings/hardware; Hopper/stand/guarding; Electrical controls.

Not included: 40–100+ hours fabrication/debugging; Workshop machinery; Compliance/inspection costs; Shipping.

Build evidence recorded 4 Sep 2026. Currency conversions are approximate.

Small granulators and workshop shredders differ materially in motor power, guarding, duty cycle and output size. The current parts estimate is useful, but a single bought price would be misleading.

BUILD AT A GLANCE

Source view and main parts

Check the source ↗

**Shredder small 3.3 with collection bins and transport trolley**Precious Plastic Headquarters · CC BY-SA 4.0Source and version ↗

Shredder 3.3 build gallery photograph · Precious Plastic / One Army ↗

PHYSICAL BUILD6 key parts or groups

No.	Source specification
01	Shredder 3.3 laser-cut/machined metal parts and fasteners from the official BOM
02	Shaft
03	Fabricated steel frame and hopper/guarding components
04	Geared electric motor and drive/coupling components specified for the chosen configuration
05	Contactor
06	Wiring

Full source specifications

Shredder 3.3 laser-cut/machined metal parts and fasteners from the official BOM
Shaft, knives/spacers and bearing assemblies from the source package
Fabricated steel frame and hopper/guarding components
Geared electric motor and drive/coupling components specified for the chosen configuration
Contactor, overload protection, safety switching, emergency-stop/control hardware and enclosure components
Wiring, terminals, protective earthing and other electrical hardware specified by the source/manual and local requirements

TOOLS / PROCESSES9 involved

Grinder
Chop saw
MIG/MAG or TIG welder
Drill press
Lathe
Laser-cutting service or suitable metal-cutting equipment
Torque wrench
Bearing mounting tools
Electrical test equipment

The real-world work

YOU STILL HAVE TOThe real-world work

Decide whether you have the fabrication and electrical competence to build this machine at all
Source or subcontract the metal cutting, turning and welding
Select and install the correct motor, contactor, overload protection and controls
Fabricate and assemble the frame, shredder box, bearings, shaft and drive
Install and verify guards, safety switching and emergency-stop provisions
Inspect alignment, fasteners, electrical protection and rotation before commissioning
Read and follow the current operating manual and local machinery/electrical requirements
Operate only with suitable sorted plastics and keep hands/tools away from the cutting chamber

THE BUILD SEQUENCE

How it comes together

1Preparation

Read the 3.3 package and operating manual before ordering
Treat the CAD, DXF, blueprints, schematics, BOM and operating manual as one system. Identify which operations require a competent fabricator/electrician and which parts will be subcontracted before buying material.
YOU
Prepare the fabrication package
Extract the correct revision files for laser cutting, turning and general metalwork. AI can help inventory drawings and flag apparent mismatches, but dimensions and revision choices must be verified against the official package.
AI + YOU
Fabricate and inspect the metal parts
Cut, drill, turn and weld using appropriate workshop processes. Inspect critical shaft, bearing, knife, frame and mounting geometry before assembly rather than relying on visual fit alone.
YOU

2Build and assembly

Assemble and align the shredder mechanism
Build the cutting box, shaft/knife stack, bearings and frame using the specified fasteners and torque/assembly methods. Confirm free movement and alignment without energising the drive.
YOU
Install drive, controls and protection
Fit the motor/drive and have the contactor, overload protection, safety circuit, emergency stopping, enclosure and protective earthing implemented and checked by someone competent for the actual supply and local rules.
YOU
Verify guarding and fail-safe behaviour
Before shredding material, inspect access to moving parts and verify the intended safety switching and stopping behaviour. Do not bypass guards or interlocks to make commissioning easier.
YOU

3Configure and test

Commission cautiously from the manual
Use the current operating manual for rotation, start/stop, loading, jam response and maintenance checks. Stop on abnormal noise, movement, heat or electrical behaviour and resolve the cause before use.
YOU
Run it as part of a controlled recycling workflow
Sort and prepare compatible plastic, control contamination, maintain the machine and store/process flakes appropriately. A shredder creates feedstock; it is not by itself a complete recycling process.
YOU

Benchmark this project

Use the Precious Plastic Shredder 3.3 prompt. Compare what different models deliver, then add what happened when you tried it.

Try this benchmark

View the project prompt

CAIBI adaptation · Prompt 1.0 · Project source

Prompt for Precious Plastic Shredder 3.3

CAIBI project benchmark: Precious Plastic Shredder 3.3
Prompt version 1.0

Help me build Precious Plastic Shredder 3.3 using the existing creator project at https://community.preciousplastic.com/library/shr---33-. This is a CAIBI benchmark adaptation of the project build brief, not a claim about how the creator used AI.

Project context:
- An open-source workshop machine that reduces sorted plastic waste into flakes for later recycling processes, with downloadable fabrication files and a documented safety-focused 3.3 revision.
- Build context: Shredder 3.3 laser-cut/machined metal parts and fasteners from the official BOM; Shaft, knives/spacers and bearing assemblies from the source package; Fabricated steel frame and hopper/guarding components; Geared electric motor and drive/coupling components specified for the chosen configuration; Contactor, overload protection, safety switching, emergency-stop/control hardware and enclosure components; Wiring, terminals, protective earthing and other electrical hardware specified by the source/manual and local requirements.
- Where AI helps: Explain the supplied CAD, drawings, BOM and assembly sequence, Help organise fabrication packages for outsourced laser cutting or machining, Cross-check dimensions and documented tolerances against the source files, Help create inspection and commissioning checklists from the official manual, Troubleshoot non-safety-critical assembly observations against the documentation.
- Physical work: Decide whether you have the fabrication and electrical competence to build this machine at all, Source or subcontract the metal cutting, turning and welding, Select and install the correct motor, contactor, overload protection and controls, Fabricate and assemble the frame, shredder box, bearings, shaft and drive, Install and verify guards, safety switching and emergency-stop provisions, Inspect alignment, fasteners, electrical protection and rotation before commissioning, Read and follow the current operating manual and local machinery/electrical requirements, Operate only with suitable sorted plastics and keep hands/tools away from the cutting chamber.
- Main limitation: The shredder combines fabricated steel parts, bearings, a high-torque drive, exposed-workshop fabrication processes and motor/control electrics. The current 3.3 revision was specifically changed around safety, but following an open design does not itself certify a home-built machine. Guarding, interlocks, electrical protection, emergency stopping, alignment and safe operating procedures require competent human judgement and local compliance checks.

Read the source first. Use its published design, files, dimensions and parts as the baseline; do not redesign it unless a missing detail requires a clearly labelled proposal. If you cannot access a source or verify a revision, say so.

Provide one practical build package:
1. Design and files: explain the source design, link the original editable files, and identify missing files or modifications.
2. Parts and fabrication: give quantities, exact variants and compatibility, plus a cutting or printing list where applicable. Preserve source dimensions; flag anything unconfirmed.
3. UK and US purchasing: direct product links, checked dates, stock, pack sizes, taxes, delivery and regional costs. Mark unverifiable details as unknown; do not invent links, prices or availability.
4. Assembly: an ordered guide covering fabrication, fitting, wiring or software as applicable, setup, checks and troubleshooting.
5. Cost and time: separate parts, fabrication, delivery, hands-on time and machine time, with assumptions and exclusions.
6. Function and ease: a test plan for the project's stated purpose, likely difficulties, required skills and any corrections or limitations.

Keep source facts, your proposals and items needing physical verification distinct. An estimate is not a measured build result. Do not claim to have built or tested hardware. Include failed attempts and omissions. If a section does not apply, say why.

Use the source as accessed during this run and record its revision or access date. The prompt is fixed; the linked source can change.

Open and copy prompt →

Benchmark results 0

No reviewed results yet for Precious Plastic Shredder 3.3. Add the first result →

AI IN THIS PROJECT

Get AI help on this build

CAIBI · AI CAN HELP

AI can help with

Explain the supplied CAD, drawings, BOM and assembly sequence
Help organise fabrication packages for outsourced laser cutting or machining
Cross-check dimensions and documented tolerances against the source files
Help create inspection and commissioning checklists from the official manual
Troubleshoot non-safety-critical assembly observations against the documentation

CAIBI · AI CAN'T DO

You still need to

Decide whether you have the fabrication and electrical competence to build this machine at all
Source or subcontract the metal cutting, turning and welding
Select and install the correct motor, contactor, overload protection and controls
Fabricate and assemble the frame, shredder box, bearings, shaft and drive
Install and verify guards, safety switching and emergency-stop provisions
Inspect alignment, fasteners, electrical protection and rotation before commissioning
Read and follow the current operating manual and local machinery/electrical requirements
Operate only with suitable sorted plastics and keep hands/tools away from the cutting chamber

Original source AI use and prompts

SOURCEThe original project does not publish an AI prompt

The prompts below are CAIBI helpers for this build. They are not presented as instructions from the creator.

CAIBI STARTING PROMPTS

Copy a prompt for this build

Each prompt tells AI to keep the original project source as the reference and to flag anything you must verify on the real build.

Ways to take it further

AFTER THE FIRST BUILD

Ways to take it further

Standard Shredder small 3.3Subcontracted fabrication with local final assemblyBike-powered derivative using the standard 3.3 shredder boxWorkspace-scale installation feeding later extrusion/injection/sheet processes

More routes and resources

OTHER WAYS TO GET THERE

You do not have to follow one route.

ORIGINAL BUILDFollow the creator route

Use the published files and instructions as the baseline.

REVIEWED RESOURCES

Useful places beyond the main source

DOCSPrecious Plastic Shredder small 3.3

Current primary build page for Shredder small 3.3, including downloadable CAD, DXF, blueprints, schematics, BOM, stated 1-2 week build duration, required fabrication skills and the operating-manual route.

DOCSPrecious Plastic Shredder workspace guide

Primary operating/workspace guidance covering space, machine acquisition, setup and explicit shredder safety guidance.

COMMUNITYBike-powered PP 3.3 build and test

Independent first-hand 2026 build based on the standard PP 3.3 shredder box, documenting physical assembly, iteration and a safer/stabler modified frame.

COMMUNITYTrash Printer builder history

Independent builder record stating that a Precious Plastic open-source shredder was physically built and used to process plastic waste before later recycling-machine development.

SOURCE · CAIBI · BUILDERS

What supports the verdict

SOURCEPrecious Plastic / One Army

The current Precious Plastic library still publishes Shredder small 3.3 as the latest Basic/small revision, with downloadable manufacturing files, a BOM, schematics, stated skills/tooling, a 1-2 week build estimate and a separate operating manual. The page says this revision addresses safety and transportability by following CE safety requirements. Independent builders document physical PP 3.3-based machines. CAIBI has not fabricated, electrically commissioned or safety-certified this machine.

Open source ↗

CAIBIBUILD FOR THE EXPERIENCE

This is workshop infrastructure rather than a casual maker project. It makes sense for a person or group that actually intends to process a recurring stream of suitable plastic and values an open, repairable machine. AI can help interpret drawings, organise the BOM, explain assembly order and reason about documented tolerances, but it does not make the fabrication or operation safe.

Evidence: Strong

BUILDERSNo published reports yet

Actual time, cost, changes and outcomes appear here after submitted builds are reviewed.

Be the first builder to report ↓

Leave a build review

HAVE YOU MADE THIS?

Leave a build review.

First-hand evidence improves the assessment

What we want to know

What happened when you actually tried to make it.

Did it work?
Actual time and cost
What did you change?
What was harder than the source suggested?
Would you build it again?