A complete design-manufacturing process for delivering customized foot orthoses by means of digital technologies is presented. Moreover, this feasibility study aims to combine a semi-automatic modelling approach with the use of low-cost devices for 3D scanning and 3D printing.

In clinical practice, traditional methods for manufacturing customized foot orthoses are completely manual, mainly based on plaster casting plus hand fabrication, and are widely used among practitioners. Therefore, results depend on skills and expertise of individual orthoptists and podiatrists that need considerable training and practice in order to obtain optimal functional devices.

On the other side, novel approaches for design and manufacturing customized foot orthoses by means of digital technologies (generally based on 3D scanning, 3D modelling and 3D printing) are recently reported as a valid alternative method to overcome these limitations.

This study has been carried out in an interdisciplinary approach between the staff of Design and Methods in Industrial Engineering and the staff of Podology with the aim to assess the feasibility of a novel user-friendly and cost-effective solution for delivering customized functional foot orthoses. More specifically, a Generative Design (GD) workflow has been developed to enable practitioners without enough CAD skills to easily 3D modelling and interactively customize foot orthoses. Additionally, low-cost devices for 3D scanning and 3D printing that have been acquired by the Podology Lab, were also tested and compared with the high-cost ones of the Department of Industrial Engineering.

The complete process is divided into three main steps. The first one regards the digitization of the patient's foot by means of 3D laser scanner devices. Then a user-friendly 3D modelling approach, developed for this purpose as GD workflow, allows interactively generating the customized foot orthosis, also adjusting several features and exporting the watertight mesh in STL format. Finally, the last step involves Additive Manufacturing systems to obtain the expected physical item ready to use.

First, for what concerns the digitizing step, the acquired data resulting from 3D scanning by means of the low-cost system (Sense 3D scanner) appears accurate enough for the present practical purposes.

Then, with respect to the 3D modelling step, the proposed GD workflow in Grasshopper is intuitive and allows easily and interactively customizing the final foot orthosis. Finally, regarding the Additive Manufacturing step, the low cost 3D printer (Wasp Delta 40 70) is capable to provide adequate results for the shell of the foot orthosis. Moreover, this system appears really versatile in reason of the capability to print in a wide range of different filaments. Therefore, since the market of 3D printing filaments is rapidly growing, building sessions with different materials (both flexible and rigid such, for example, PLA, AB and PETG) were completed.

This study validated, in terms of feasibility, that the use of a GD modelling approach, in combination with low-cost devices for 3D scanning and 3D printing, is a real alternative to conventional processes for providing customized foot orthosis. Moreover, the interdisciplinary approach allowed the transfer of skills and knowledge to the practitioners involved and, also, the low-cost devices Sense 3D scanner and Wasp Delta 40 70 that have been acquired by the Podology Lab, were demonstrated suitable for this kind of applications.