Instrumental Accessibility in Technical Drawing teaching: development and validation of an adapted compass via additive manufacturing

Abstract

The democratization of access to higher education, driven by the Brazilian Inclusion Law, has brought new challenges related to academic retention and participation, particularly in Engineering, Architecture, and Design programs, which require complex graphical skills. Technical Drawing, traditionally taught through a predominantly visual approach, represents a significant instrumental barrier for students who are blind or have low vision, mainly due to the scarcity of adapted tools capable of translating geometric concepts into tactile-kinesthetic representations. This study aimed to develop and prototype an accessible compass using Additive Manufacturing as a means of democratizing access to Assistive Technology. The methodology adopted a user-centered development approach, structured around iterative cycles of contextual analysis, design, and practical evaluation. Based on a benchmarking process that confirmed the lack of commercially available solutions and on the selection of an open-source model from digital repositories, a Morphological Matrix was applied to define design requirements, followed by parametric modeling in CAD software and 3D printing using PLA. The results of the initial prototyping cycles revealed critical technical limitations: the resolution of Fused Deposition Modeling (FDM) printing in small-scale components made Braille numbering impractical due to insufficient physical space and inadequate tactile definition. Subsequent design iterations led to the incorporation of a fixed needle point to ensure greater stability during one-handed use and, more significantly, to the complete removal of Braille in favor of an intuitive hole-counting system. Final user validation confirmed that simplifying the design increased its effectiveness, enabling the autonomous construction of circles. It is concluded that the integration of User-Centered Design and 3D printing enables the decentralized production of low-cost Assistive Technology, helping to address gaps in the commercial availability of adapted instruments. The study demonstrates that effective Instrumental Accessibility does not depend on technological complexity, but rather on ergonomic adequacy to the user’s actual haptic perception needs, thereby promoting equity in spatial learning.