Challenges in Sustainability | 2014 | Volume 2 | Issue 1 | Pages 30‒40
DOI: 10.12924/cis2014.02010030
Research Article
Reversing the Trend of Large Scale and Centralization in
Manufacturing: The Case of Distributed Manufacturing of
Customizable 3-D-Printable Self-Adjustable Glasses
Jephias Gwamuri
, Ben T. Wittbrodt
, Nick C. Anzalone
, Joshua M. Pearce
The Michigan Tech Open Sustainability Technology (MOST) Laboratory, 601 M&M Building, 1400 Townsend
Drive, Houghton, MI 49931-1295, United States; E-Mail: (JG), (BTW), (NCA)
Department of Materials Science & Engineering, Michigan Technological University, 601 M&M Building, 1400
Townsend Drive, Houghton, MI 49931-1295, United States
Department of Electrical & Computer Engineering, Michigan Technological University, 601 M&M Building, 1400
Townsend Drive, Houghton, MI 49931-1295, United States
* Corresponding Author: E-Mail:; Tel.: +1 9064871466
Submitted: 29. May 2014 | In revised form: 22. August 2014 | Accepted: 22. October 2014 |
Published: 12 December 2014
Abstract: Although the trend in manufacturing has been towards centralization to leverage
economies of scale, the recent rapid technical development of open-source 3-D printers enables
low-cost distributed bespoke production. This paper explores the potential advantages of a
distributed manufacturing model of high-value products by investigating the application of 3-D
printing to self-refraction eyeglasses. A series of parametric 3-D printable designs is developed,
fabricated and tested to overcome limitations identified with mass-manufactured self-correcting
eyeglasses designed for the developing world's poor. By utilizing 3-D printable self-adjustable
glasses, communities not only gain access to far more diversity in product design, as the glasses
can be customized for the individual, but 3-D printing also offers the potential for significant cost
reductions. The results show that distributed manufacturing with open-source 3-D printing can
empower developing world communities through the ability to print less expensive and customized
self-adjusting eyeglasses. This offers the potential to displace both centrally manufactured
conventional and self-adjusting glasses while completely eliminating the costs of the conventional
optics correction experience, including those of highly-trained optometrists and ophthalmologists
and their associated equipment. Although, this study only analyzed a single product, it is clear that
other products would benefit from the same approach in isolated regions of the developing world.
Keywords: additive layer manufacturing; development; distributed manufacturing; eye care;
glasses; 3-D printing
© 2014 by the authors; licensee Librello, Switzerland. This open access article was published
under a Creative Commons Attribution License (
1. Introduction
The history of mass production predates the industrial
revolution and was initially motivated by the need to
equip large armies with standardized weapons, but by
the end of the 19th century the production of large
amounts of standardized products on assembly lines
became widespread and central to economics [1‒3].
The benefits of large-scale manufacturing (or flow
production) are well established and include reduction
in costs due to the economies of scale from: i) bulk
purchasing of materials, supplies, and components
through long-term contracts; ii) technological advan-
tages of returns to scale in the production function,
such as lower embodied energy during manufacturing
of a given product because of scale; iii) favorable
financing in terms of interest, access to capital and a
variety of financial instruments; iv) marketing and v)
increased specialization of employees and managers
[4‒6]. These advantages have created a general trend
towards large-scale manufacturing in low-labor cost
countries, especially for inexpensive plastic products
Centralized and mass manufactured goods are
often still unaffordable to remote communities of the
developing world because of proportionally large dis-
tribution and transportation costs [9]. These trans-
portation costs have a concomitant embodied energy
and environmental impact of transportation that can
be substantial [10]. Centralized manufacturing, thus is
deficient in two fronts; cost in the developing world
and environmental impact. A sustainable manufac-
turing system with optimized value calls for a broader
and more holistic view than lowest unit cost of pro-
duction and points to the potential for distributed
manufacturing systems encompassing engineering-
management aspects, economic and technical issues,
environmental drivers and social implications [11,12].
Until recently there was no technology capable of
providing the necessary low costs and the ability to be
distributed to isolated regions.
3-D printing offers a novel form of localized and
customized production and is an emerging 21st cen-
tury innovation platform for promoting distributed
manufacturing systems [13‒18]. The technological
development of additive manufacturing with 3-D print-
ers has been substantial [15,16], which has benefited
many industries; however, the costs of 3-D printers
have historically been too high to be feasible for
distributed or home-based manufacturing [19]. Re-
cently, several open-source (OS) models of commer-
cial rapid prototypes have been developed [19], which
offer an alternative model of low-cost production. The
most successful of these is the self-replicating rapid
prototype (RepRap), which can be built from 3-D
printed parts, open-source electronics, and common
hardware for about $500 [20,21]. Using computer
aided design (CAD) customized (shapes and designs)
prototypes can be produced quickly and economically
[22] and there is evidence the RepRap can fabricate
products less expensively than conventional manufac-
turing [23]. Distributed manufacturing using low-cost
open-source 3-D printers has been shown to generally
have the potential of reducing the environmental
impact, in particular for plastic products [14‒17,24] as
the nature of 3-D printing allows for the minimization
of production waste while maximizing material util-
ization [19,25,26]. Furthermore, distributed manufac-
turing in the form of open-source appropriate 3-D
printing technology, combined with distributed gener-
ation (solar photovoltaic powered 3-D printers), has the
potential to alleviate poverty in impoverished rural
communities in the developing world [18].
This paper explores the potential advantages of a
distributed manufacturing model of high-value prod-
ucts by investigating eyeglasses, which are currently
only mass-manufactured for the reasons detailed
above. Specifically, this paper reports on a case study
of 3-D printable self-adjustable glasses by first review-
ing the potential market for low-cost corrective glass-
es and then the limitations of centrally mass-manu-
factured self-adjustable glasses. Then a series of pa-
rametric 3-D printable designs is developed to over-
come each of the identified limitations as a proof of
concept. The results are analyzed for this case study
and conclusions are drawn about the potential rever-
sal of the manufacturing trend of centralization.
2. Case Study
The World Health Organization (WHO) estimates that
globally about 314 million people are visually im-
paired, of whom 45 million are blind [27]. The WHO
predicts that 80% of all visual impairment is avoidable
(can be prevented or cured). The global distribution of
avoidable blindness based on the population in each
of the WHO regions is: South East Asian 28%,
Western Pacific 26%, African 16.6%, Eastern Mediter-
ranean 10%, American 9.6%, and European 9.6%
[27]. With almost 90% of blind and visually impaired
people living in low- and middle-income countries,
including some of the world's poorest communities,
access to eye care is often unavailable [27,28].
Globally 153 million people over 5 years of age are
visually impaired as a result of uncorrected refractive
errors (URE) [29].
Conventional approaches to correcting URE are
firmly rooted in the health-care sector and involve
having an eye care professional perform an eye exam-
ination to determine the general health of the eye and
whether eyeglasses are required to improve vision
[30]. Correcting URE requires both specialized
complex equipment and professional eye specialists
ophthalmologists, optometrists/refractionists and opti-
cians—to implement effectively. However, access to
eye care and hence eyeglasses is severely limited in
the developing world due to an acute lack of profes-
sionals and financial resources to provide adequate
eye care services. For some cases in Africa: South
Africa has approximately 2400 eye care practitioners
servicing a population of roughly 47 million people
[30] a ratio of approximately 1:20,000 whilst in Ghana
the ratio of trained eye care professionals to members
of the public is 1:200,000 [31,32] and approximately
1:1,000,000 for the case of Ethiopia [30]. These ratios
are far less than the WHO recommended standard for
2010 of one refractionist per 100,000 population [27].
The African WHO region with 70.5 million estimated
cases of vision impairment due to uncorrected re-
fraction errors have a total of 4,985 existing functional
clinical refractionist and thus requires an additional
10,138 [33]. Similarly, the South-east Asia region
(196.2 million visual impairment cases) has 12,415
existing functional refractionist requiring an additional
21,651 [33]. Using a conventional approach this would
require over $2,000 million for training the additional
personnel and establishing new refraction care facilities
over a 5 year period in Africa, and over $3,450 million
for South-east Asia for the same period of time [33]. A
full functional practice requires clinical refractive
equipment, ocular health screening equipment, oph-
thalmic dispensing equipment and accounting and
business equipment as well as the cost of start-up
stock [33]. The Digital Refraction Systems alone can
cost well in excess of $33,000 and ophthalmic dis-
pensing equipment prices can be well over $10,000
[34]. Therefore, to establish a facility with basic
equipment can cost over $100,000. Automated re-
fraction requires access to expensive machines, which
must be adequately maintained and calibrated and
are mostly unsuitable for remote off-the grid com-
munities and hence not a viable option. The ratio of
ready-made to custom-made spectacles can be as-
sumed to be 20 to 80, which is in line with expec-
tations in the developed world [33,35]. Current
market prices for ready-made prescription eyeglasses
range from less than $7 online to over $1,000 from
the optometrist [36]. This eyeglass price is currently
beyond the budget of many developing world com-
munities whose cost of living is less than a $1.25 per
day. According to the World Bank report, more than
1.22 billion people in the developing world are living
below this extreme poverty baseline [37].
The general steps in the provision of refraction
services [27] can be summarized as in Figure 1.
A potential solution to this problem is self-refraction
through the use of Silver's revolutionary self-adaptive
eyeglasses [38,39]. Adjustable eyeglasses (Adspec
lens/glasses) offer the user the ability to change the
power of each adaptive lens independently to improve
vision in each eye: a process known as self-refraction,
a potential solution to the shortfall in eye care profes
Figure 1. The general steps in the provision of
refraction service.
sionals in developing countries. Self-adjusting eye
glasses thus provide a means of both measuring and
correcting refractive error in regions underserved by
eye care professionals. The use of wearer adjustable
eyeglasses solves two problems: first, it reduces the
need for measurement by a trained refractionist,
which is crucial for regions with few eye care profes-
sionals. Secondly, it offers a much simpler and far
cheaper deployment compared to a more conven-
tional approach based on lens grinding or stock optics
[30,38‒42]. Self-adjusting eyeglasses would make
vision correction accessible particularly to those in the
developing world where there is either a lack of pro-
fessionally trained optometrists and ophthalmologists,
or where the cost of traditional spectacle lenses and
professional consultation is prohibitively expensive [42].
The Adspec lens is composed of two thin circular
membranes sealed at the edges and filled with a fluid
with an index of refraction,
of 1.579 [42]. The
optical power of the lens is a function of the surface
curvature, which is determined by the volume of the
fluid in between the membranes. Hence by varying
the fluid volume, the optical power of the lens can
also be varied to the desired value. Mounting two
adaptive lens on a specialized spectacle frame results
in an adaptive spectacles (Adspecs) [42], which offers
the user to ability to adjust the refractive power of
each lens to achieve self-refraction. The useful power
range of the lenses was reported to be −6 D to +12 D
[42]. Preliminary field trials to determine the effec-
tiveness of the Adspec lenses as a means of vision
correction were performed both in selected African
and Asian countries with promising results [3843].
Vision correction using self-adjusting spectacles can
be summarized as in Figure 2.
Adspecs have the potential for achieving Vision
2020; a partnership between the World Health Organ-
ization (WHO) and the International Agency for the
Prevention of Blindness (IAPB) launched in 1999 with
the twin aims of eliminating avoidable blindness by
the year 2020 and preventing the projected doubling
of avoidable visual impairment between 1990 and
2020 [27,28]. Adspec technology can be considered a
great success, however, the deployed Adspecs have
four remaining challenges: 1) the frame is highly frag-
ile, which makes it potentially inappropriate for chil-
dren and adults whose job involves manual labor (see
Figure 3), 2) the costs are too high for target com-
munities with low incomes, 3) people of different age,
gender, ethnicity and geographical locations have vari-
able widths between their eyes, which does not allow a
one-size-fits all mass manufacturing of Adspecs, and 4)
they are not aesthetically appealing and socially ac-
ceptable for many teenagers (i.e. they are not cool).
The first generation of Adspecs tended to break at the
hinge and users would use duct tape to make them
operational as seen in Figure 3a and 3b, which did not
assist with aesthetics and long term use.
Figure 2. Adaptive spectacles self-refracting
Figure 3. a) Detail of hinge break on an Adspec lense and b) the Adspec system fixed with duct tape.
The use of open source appropriate techniques
(OSAT) [44] such as open source 3-D printing has the
potential to solve all four challenges. The first problem
can be easily overcome by varying the thickness, print-
ing density or combining different materials to achieve
the desired strength at the hinge. Second, cost reduc-
tions of up-to 95% have been demonstrated for the
open source 3-D printing of optics equipment [45] and
the 3-D printing of common household products has
been shown to be substantially lower than mass
manufacturing retail costs, neglecting additional ship-
ping and tax charges [23]. One major advantage of dis-
tributed fabrication is the ability to customize the
products to meet specific individuals' or groups' needs.
Customization provides the flexibility to selectively
fabricate eyeglass frames to each individual's taste and
eye spacing making the self-adjusting spectacles both
appealing and comfortable to wear, solving challenges
3 and 4. Youth can be afforded an opportunity to
design their own eyeglass frames according to their
preferred shape, decoration and color. The experiments
described below aim to provide a proof of concept for
overcoming these four challenges with open-source
distributed manufacturing.
3. Experimental
The entire software and hardware tool chain for the
design and fabrication of the glasses used open-
source technology, starting with a desktop computer
running Debian 7.1 ( The
glasses were designed using OpenSCAD 2013.06 [46],