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3D-printed metamaterial device reflects sound perfectly

While researchers have proposed many theoretical approaches to engineer such a device, they’ve struggled to simultaneously control both the transmission and reflection of sound in exactly the desired manner, and none have been demonstrated experimentally.

The new design is the first to demonstrate complete, near-perfect control of sound waves. 3D printers can quickly and easily fabricate the design.


... is a method to design the equivalent of optical devices for sound, based on acoustic metamaterials. Our contributions include: how to design compact acoustic lenses; how to transform a standard speaker into a directionalone; how to build and adjustable focus acoustic lens i.e. the equivalent of a zooming objective for light.

Ultrathin Acoustic Metasurface-Based Schroeder Diffuser

“Schroeder diffuser” is a classical design, proposed over 40 years ago, for artificially creating optimal and predictable sound diffuse reflection. It has been widely adopted in architectural acoustics, and it has also shown substantial potential in noise control, ultrasound imaging, microparticle manipulation et al. The conventional Schroeder diffuser, however, has a considerable thickness on the order of one wavelength, severely impeding its applications for low-frequency sound. In this paper, a new class of ultrathin and planar Schroeder diffusers are proposed based on the concept of an acoustic metasurface. Both numerical and experimental results demonstrate satisfactory sound diffuse reflection produced from the metasurface-based Schroeder diffuser despite it being approximately 1 order of magnitude thinner than the conventional one. The proposed design not only offers promising building blocks with great potential to profoundly impact architectural acoustics and related fields, but it also constitutes a major step towards real-world applications of acoustic metasurfaces."

Bang Olufsen expired patents

The infamous reflector and a great idea for a 3D printed project ;)

Some ideas for a smart bike pollution meter

Using an Arduino UNO and a PPD42NS.

Asmograf Pen Plotter

"Some time ago I got a bit nostalgic about a pen plotter from 80's called Alfigraf. It was produced in Czechoslovakia and based mainly on parts of a construction kit called Merkur (fun fact - first contact lenses were created using machine built from Merkur). Long story short, first I built the plotter using Merkur parts and then I decided to make a design for 3D printing so I could put the Merkur parts back to the box."

D3D Universal

D3D Universal - Open Source Ecology

Make a Mini CNC Plotter

Just recycle old DVD players into a mini CNC Plotter based on Arduino.

A freeform singlet lens design free of sphericalaberration

An analytical closed-form formula for the design of freeform lenses free of spherical aberration is presented.Given the equation of the freeform input surface, the formula gives the equation of the second surface in orderto correct the spherical aberration. The derivation is based on the formal application of the variational Fermatprinciple under the standard geometrical optics approximation.

Direct granules extruder

Waste plastics has to be shred into granules. The size of the granules is an important property of the raw material for an extruder. Here I have shred PLA using a blender. PET from old plastic bottles is another source of material that is currently part of my first test series.

Trash Printer - Recycled Plastic 3D Print Head

"So I began to modify the Precious Plastic design, putting it on a vertical axis and trying to make it light enough to fit on a CNC router gantry, and power it with a stepper motor so that it could be controlled using existing 3D printing software. After many iterations, I finally got it printing this Spring, and the results have been very promising!"


µCube is a framework for optomechanics design, which is compatible with 3D printing. It is also an assembly standard for designing, building and sharing optical modules. µCube is implemented using OpenSCAD, a programming language for CAD modelling. This allows every component to be described as a parametric model, which can be easily shared in a form of a code.

3D printing courses

Low-budget 3D-printed equipment for continuous flow reactions

Get it here.

The OpenFlexure Microscope

The OpenFlexure Microscope is a 3D printable microscope.

Raspberry PI + ROS

A few links and sources about building a first robot:

Making RepRap prints stronger without doing a lot of work

"It occurred to me that this could be generalised to make prints that acted like glass-fibre or carbon-fibre reinforced resin for extra strength. Think about what happens if, in the CAD system, you subtract a thin cylinder (say 0.5mm in diameter) from the interior of a part to be printed. When the part is sliced the slicer will surround the cylinder with solid material automatically, making it like a length of strong fibre embedded in a weaker material (the print’s infill)."

Huge Arduino Based Dot Matrix Printer


General Support-Effective Decomposition for

We present a method to fabricate general models by multi-directional 3D printing systems, in which different regions of a model are printed along different directions. The core of our method is a support-effective volume decomposition algorithm that targets on minimizing the usage of support-structures for the regions with large overhang.

Portal Point Generator

An efficient and compact generator that can be coupled with wind turbines or water wheels to produce upwards of 100W.

Large Volume Paste Extruder

This extruder is designed to push a large volume of paste trough a bowden-style tube and into your choice of nozzle.

Paste Extruder—Hardware Add-On for Desktop 3D Printers

This paper presents the design, development and testing of a paste/clay extrusion device intended to be used as a drop-in replacement for the conventional thermoplastic extruder of a desktop filament-based 3D printer


Open-source syringe extruder

Get it here:

Paper pulp 3dprinter

A paper revolution is coming! From both my interest in sustainability and fascination for tools and techniques grew the idea of a 3D printer to recycle paper.

3D printed DELTA robot

The goal of this project is to build a DELTA robot in which all parts may be 3D printed.

Toward the Coevolution of Novel Vertical-Axis Wind Turbines

The production of renewable and sustainable energy is one of the most important challenges currently facing mankind. Wind has made an increasing contribution to the world's energy supply mix, but still remains a long way from reaching its full potential. In this paper, we investigate the use of artificial evolution to design vertical-axis wind turbine prototypes that are physically instantiated and evaluated under fan generated wind conditions. Initially a conventional evolutionary algorithm is used to explore the design space of a single wind turbine and later a cooperative coevolutionary algorithm is used to explore the design space of an array of wind turbines. Artificial neural networks are used throughout as surrogate models to assist learning and found to reduce the number of fabrications required to reach a higher aerodynamic efficiency. Unlike in other approaches, such as computational fluid dynamics simulations, no mathematical formulations are used and no model assumptions are made.

3d printed wind turbine

A 3d printed wind turbine for generating electricity that could be applied to lots of scenarios due to its scale.

Edge Machine Learning

This paper develops a novel tree-based algorithm, called Bonsai, for efficient prediction on IoT devices – such as those based on the Arduino Uno board having an 8 bit ATmega328P microcontroller operating at 16 MHz with no native floating point support, 2 KB RAM and 32 KB read-only flash.



Coffee maker parallel robot 3D printer

There are many diy 3D printer designs available on the internet, this one is different.

Idea for a robot

An object of the present invention is to provide a manipulator which has dexterity similar to the human arm.

Arduino mobile robot

A nice 3d printed model.

Hexy a light-seeking robot

Note: great idea for an Arduino robot ;)

Criado/Created: 2018

Última actualização/Last updated: 26-02-2020 [16:12]

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(c) Tiago Charters de Azevedo