Fab FM: the Design, Making, and Modification of an Open-Source Electronic Product

David A. MellisMIT Media Lab75 Amherst St.

Cambridge, MA 02142 USAmellis@media.mit.edu

Dana GordonMIT CAVS

265 Massachusetts Ave.Cambridge, MA 02139 USA

d_gordon@mit.edu

Leah BuechleyMIT Media Lab75 Amherst St.

Cambridge, MA 02142 USAleah@media.mit.edu

ABSTRACTThis paper explores the ways in which digital fabricationallows for the small-scale manufacture and individualcustomization of consumer electronic products. We presentFab FM, an open-source FM radio that integrates anelectronic circuit board, laser-cut wood, and fabric. Wedescribe a workshop in which participants designed andbuilt their own Fab FM variants, modifying the form,materials, and behavior of the radio. Drawing from thisexperience, we discuss three themes: the issues involved inworking across design domains, the ways in which designcan serve as source code, and the difference between open-source and hackable. We present potential business modelsfor Fab FM, and discuss the possibilities that digitalfabrication offers for a more diverse landscape of high-techproducts.

Author KeywordsDigital fabrication, open-source hardware, consumerelectronics, mass customization, DIY, design.

ACM Classification KeywordsJ.6 Computer-Aided Engineering.

General TermsDesign, Economics.

INTRODUCTIONThe spread of digital fabrication (machines that can produceobjects directly from digital design files) is makingmanufacturing accessible to a growing audience [2].Products can be designed with commonly-used drawingsoftware or low-cost CAD programs. Services like Ponoko[9] (for laser cut products), Shapeways [13] (for 3d-printedobjects), and BatchPCB [4] (for circuit boards) allowindividuals to order one or more physical objects from thesedigital files, and provide marketplaces where others canorder additional copies of the designs. The proliferation offab labs [7] and other digital fabrication facilities allow

their members to produce objects on demand and to rapidlyiterate through multiple versions of a design. Low-costrapid prototyping and CNC machines (e.g. [8] and [11])make it increasingly feasible for individuals to establishtheir own digital fabrication capability. It's now possiblefor anyone to design a product, prototype it, and thenmanufacture arbitrary additional copies with the same filesand processes.

This growing availability of the software to design objectsand the machines to produce them makes it increasinglyrelevant to share designs with others. Many people publishtheir files online using sites like Thingiverse [14], whichcollect files for a variety of fabrication machines. Thisactivity has accompanied the development of the concept ofopen-source hardware, paralleling that of open-sourcesoftware. It shares the beliefs that users of a product shouldbe able to study its design, make modifications to it, andshare the design and modifications with others (i.e. the fourfundamental freedoms listed by the Free SoftwareFoundation). Although complicated by the fact thatadditional resources are required to create a physical objectfrom its design, open-source hardware is gaining inprevalence, with examples like the Arduino microcontrollerdevelopment platform [3] and the Bug Labs modularhardware platform [5].

Some companies (e.g. Adafruit Industries [1] and Evil MadScientist Laboratories [6]) have begun to apply digitalfabrication and open-source hardware to consumerelectronic products. These companies produce kits whichcombine electronics and laser-cut or other structural parts.These are then assembled by customers into completeelectronic products. The economics of digital fabricationallow for relatively small production runs (in the hundredsor thousands). This type of production occupies a spacesomewhere between traditional manufacturing (with itslarge capital expenditures and up-front tooling costs) andhandmade goods (which must be individually crafted bytheir maker). It makes viable products which would be tooexpensive to make individually but that lack the market sizeneeded for mass manufacture.

Several research projects have used digital fabrication as atool for making prototypes of construction kits (e.g. [10],[16]). Plywood Punk [12] provides an interesting exampleof a product that integrates electronics with laser-cut

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wooden parts. Spatial Sketch [15] shows the potential ofdigital fabrication for the customization of products.

Fab FM is an open-source FM radio, our case study in theuse of digital fabrication for the manufacture of anelectronic product. Through it, we hope to understandwhether such processes can yield devices which arefunctional, desirable, and economically viable. We are alsoinvestigating the potential that digital fabrication offers formodifying or customizing the design of the product and thealternative business and distribution models that it allows.

This paper starts by describing the components andconstruction of the Fab FM. It then discusses a workshopin which participants built their own versions of the radio,showing some of the possibilities for customization allowedby this type of production process. It highlights three largerthemes emerging from the workshop. Then, it describessome of the possible business models for furthermanufacturing and distribution of the radio. Finally, itreflects on the larger implications for digital fabrication andopen-source hardware.

DESIGNIn designing Fab FM, we drew on the materials and formsof classic radios while taking advantage of the productionprocesses allowed by digital fabrication. The electronicsand casing were designed in parallel to ensure simplicity ofconstruction and ease of assembly. This was complicatedby the necessity of using separate software design tools forthe electronics and the structure, but eased by the rapidtesting and iteration allowed by digital fabrication.

At the heart of the radio is a digital FM receiver controlledby a microcontroller, whose output is sent through anamplification circuit to the speaker. The structure of theradio is provided by a laser-cut plywood frame, with a frontand back face held together by press-fit horizontal struts.This technique allows the faces to take on any shape, andwe choose a curve to highlight this flexibility. Theelectronic circuit board rests on a cut-out in the frame.Carefully positioned holes in the front face help to supportthe knobs, which are soldered to the PCB. The speaker issecured in a circular cut-out by fabric glued to the plywood.The frame is then wrapped with another piece of fabric,paper, or other soft material. Laser-cut veneer or othermaterial is attached to the front and back faces.

In its current form, Fab FM isenvisioned as a kit of parts tobe assembled by the user. These include the PCB,electronic components, laser cut plywood and veneer, andpossibly the fabric. Within this format, however, we seeseveral possibilities for variation. The separation of thestructure and skin in the design of the radio allows users toselect their own soft materials, giving the object a personalsignificance. With a little extra work, the front and backveneer faces could be replaced with another material, handcut to the appropriate shape. The laser cut pieces weredesigned in Adobe Illustrator and Inkscape, making them

straightforward to modify for the many users of thesepopular software packages. Modified forms could then beproduced by the manufacturer of the Fab FM kit, by anindividual with access to a laser cutter, or through a servicelike Ponoko. The design of the electronic circuit board canbe edited with the freeware version of Eagle, a CADpackage popular with hobbyists. Modified circuits couldthen be etched, milled on a CNC machine, or ordered froma service like BatchPCB. The radio’s firmware can becompiled with the open-source GCC and uploaded via aprogramming socket on the circuit board.

WORKSHOP AND VARIATIONSTo explore the possibilities for customization of Fab FM,we held a one-day workshop in which participants wereasked to design and construct their own variations on theradio. We invited people we thought likely to be especiallycreative in the modifications; eleven attended (seven menand four women). The workshop was held in the authors’lab space, which offered access to soldering irons, a lasercutter, and miscellaneous supplies. Each participant wasprovided with a kit containing the Fab FM circuit board andelectronic components; the other materials needed toconstruct the standard design (e.g. plywood and fabric)were on hand. The workshop began with an introduction tothe kit and the sharing of participants' ideas for their radios.Most of the day was spent designing and building Fab FMvariants, which were presented and documented at the endof the workshop.

Participants quickly identified ideas for modifications to thedesign of the radio, including:

• harvesting energy from vibrations caused by soundwaves hitting the speaker,

• speaking aloud the frequency of stations as the radiowas tuned,

• analyzing the received audio signal in order to tune to astation with particular musical qualities,

Figure 2. The Fab FM kit.

Figure 1. An assembled Fab FM.

• constructing the speaker from laser-cut plywood, amagnet, and an electromagnet,

• a miniature version of the radio that also functions as anightlight,

• using fabric matching a friend's newly handmadecurtains, and

• tuning only to the one or two stations listened to by theintended user.

Although it was a struggle to both customize and build aradio within the day, many participants finished with a solidbasis for their own Fab FM variation. Three participantscreated aesthetic variations on the case: one using curvedtransparent acrylic to reveal the electronics inside, oneminiature version, and one square-shaped design with laser-etched text. Two participants constructed a prototype of theplywood speaker. One participant customized the Fab FMfor a particular user, his girlfriend, using a fabric matchingher curtains and modifying the radio’s software to tune toher two favorite stations. Two other participants alsomodified the interface to the radio: one replaced the tuningknob with buttons for seeking up and down, while anotherevenly distributed the available stations across the range ofthe knob’s movement. One participant tweaked theamplifier circuit to find the maximum volume possiblewithout distortion. Another modified the design of the PCBin order to mill it on a CNC machine of his own design andconstruction.

Overall, we saw three main dimensions of customization:shape / form, materials, and behavior / functionality. Thesemodifications seem to reflect participants’ skills andinterests as well as the relative accessibility of variousfabrication processes. Given the availability of a lasercutter, participants were able to design, prototype, andconstruct modifications to the shape of the radio with littleassistance. Changes to the materials and appearance weresimilarly straightforward. Modifying the behavior of theradio, however, was more difficult. Participants were ableto customize the physical interface (i.e. knobs and buttons)more-or-less on their own, but the corresponding changes tothe code required either a strong background inprogramming or close assistance.

DISCUSSIONSeveral interesting themes emerged from the workshops.These are discussed below.

Working Across Multiple Design DomainsThe workshop illustrated some of the issues involved indesigning across multiple domains (code, circuit, andphysical structure). First, it showed the value of a standardkit or pre-existing design as a default for people who onlywant to customize one aspect of a product. Second, ithighlighted the significance of those elements of the designthat must correspond between domains (e.g. the distancebetween the radio’s knobs, or the microcontroller pinchosen to read from the tuning knob). It also showed therelative ease with which the design can be changedprovided those correspondences are respected. Thissuggests possibilities for design tools that help peopledesign across multiple domains or work within a particularone while maintaining compatibility with another.

Design as Source CodeBecause the case is fabricated directly from a digital file,the modified radios are not simply one-of-a-kind, handmadeobjects. In creating their individual radios, the workshopparticipants frequently generated new digital files that couldbe replicated by others, making them designs in their ownright. This is the essence of open-source as applied tohardware: a process in which new versions of a design caneasily be shared, studied, produced, and further modified orcombined. It stands in contrast to both craft processes, inwhich modifications likely don’t exist in a digital form thatcan be easily replicated, and mass manufacture, in whichtooling costs often make it infeasible to produce customvariations on a design.

Open-Source vs. HackableIn addition to investigating the possibilities allowed by theopen-sourcing of the designs for hardware, the workshoprevealed other ways in which the Fab FM design could bemade hackable. For example, participants seemed reluctantto add components to the circuit, despite having thenecessary documentation and, in some cases, a clear ideafor additional electronic functionality. The breaking out ofadditional microcontroller pins and the audio signals, along

Figure 3. Fab FM variants made by workshop participants.Figure 2. The Fab FM kit.

with a prototyping area on the PCB, might encouragemodification to the circuit. Documentation embeddeddirectly within the CAD files for the case would havehelped people understand which parts they could modifyand which dimensions were determined by other constrains(e.g. the circuit board or the material thickness). Sourcecode written using the Arduino libraries and conventions(instead of standard AVR C) would have been accessible tomore of the participants. In general, it seems that whilemaking a design open-source gives people the formalpermission to modify it, it may be other qualities thatactually encourage them to do so.

BUSINESS MODELSOne goal of Fab FM is to explore the economics andfeasibility of various potential production processes andscales. Table 1 presents the overall costs of componentsand materials for one, ten, and one hundred copies of theFab FM. Presentations by Adafruit Industries and otherssuggest that the typical retail price for such products isaround twice the component cost. This ratio suggests aselling price of around $80, comparable to that charged forsimilar kits from Adafruit and Evil Mad ScientistLaboratories. The success of those products suggest thatthis is a viable product, at least for the specific audience ofDIY enthusiasts. Total investment in prototypes and thekits used in the workshop was less than $1000. Thedevelopment was carried out by two individuals over thecourse of a few weeks. It has yielded a design andproduction process that should be able to scale to 100s orpossibly 1000s of kits. In these ways, we feel it provides aninteresting model for the development and distribution ofother open-source electronic products.

We envision a number of possible alternative productionand distribution models for Fab FM. It could be sold with apre-populated circuit board, allowing it to be constructedby those interested only in the craft aspects. We (or others)could provide a service which would assemble a finishedFab FM from materials supplied by the customer, yielding apersonalized object from a standard manufacturing process.Variations on the radio could be sold as their own kits forpeople who prefer those designs. Finally, an individualcould create their own radio directly from the design files,using services like BatchPCB and Ponoko.

CONCLUSION AND FUTURE DIRECTIONSFab FM illustrates some of the possibilities for the digitalfabrication of consumer electronic products. It shows howcareful design can create an object which is attractive,easily prototyped and manufactured in small quantities, andamenable to modification. The workshop demonstratesthat, given the opportunity, people are interested and able tocustomize electronic products in multiple ways, includingform, materials, and functionality. The potential businessmodels suggest that digital fabrication is a viable approachto the manufacture of electronic products, one which allowsfor an increased diversity of processes and objects.

The domain of digitally fabricated electronic productsseems rich with possibilities. In the future, we hope toexplore both the market potential of the Fab FM as well asthe possibility for the design and manufacturing of othersimilar products. We also see opportunities to create toolsthat help people design across multiple domains (e.g.electronics, structure, and code). We view Fab FM as aninitial exploration in an exciting space.

ACKNOWLEDGMENTSThanks to Neil Gershenfeld and the workshop participants.

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Are the New Bits. Wired Magazine, Feb 2010.3. Arduino. http://www.arduino.cc/4. BatchPCB. http://batchpcb.com/5. Bug Labs. http://www.buglabs.net/6. Evil Mad Scientist Laboratories.

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Desktop--From Personal Computers to PersonalFabrication. Basic Books, 2007.

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Quantity x1 x10 x100Components $38 $35 $29PCB $33 $6 $5Materials $12 $5 $5Total $83 $46 $39

Table 1. Cost of the parts for Fab FM in various quantities.