This graduation thesis presents the results of the design of a sustainability inspired materials selection app for designers. Sustainable design, and in specific ecodesign plays an increasingly important role in society. However, industrial designers, being uniquely suited to take such considerations into account, have difficulty in finding the right tools for the job. To make the selection of materials with a low environmental impact easier and more accessible, Excel based look- up tables have been developed (available at www.ecocostsvalue.com) by Delft University of Technology. However, designers still struggle with choosing the right materials, think the process is too time consuming and lack the necessary support and inspiration to perform the task ahead. Context In order to provide a solution, an extensive referencing framework was created by using literature studies, interviews, and by doing a study of existing ecodesign tools. This framework was used to identify the points of attention, areas that were considered lacking in the existing Excel based look-up tool, but also in other existing tools. By deciding on the format of a (smartphone) app, and making it LCA based, a tool was envisioned that could be used parallel to the design process; thereby providing maximum value. The tool was created in several phases, the first included a theoretical framework as has just been discussed. The second phase included the creation of a mockup design, which allowed for fast optimisations to be made to the interface following user testing involving industrial design students. Many iterations later, after the conceptual design had taken shape, the actual programming began for an iOS prototype version of the app; and even in that state the testing continued. By making use of TestFlight, a beta app distribution platform provided by Apple, several in-between versions of the app were distributed to testers for feedback. The entire process resulted in a continuously evolving prototype. Idemat app The resulting app, named: Idemat - after its backing dataset (the dataset of the app is based on an app optimised version of the Idemat 2015 Excel database) - offers significant value over existing tools. It contains a large and accurate dataset offering two single indicators, and has a clear navigational structure that is easy to understand and navigate. It offers explanatory background information, providing an educational aspect to the user; the latter by including descriptive texts, images and by visualising the impacts of choices made regarding their end-of-life impact. The app is fast, lightweight and user-friendly, and is programmed with future functionality in mind. Besides this, it is highly visual and aims to inspire designers, challenging them to think further, to reach farther. Future The future looks bright for the tool, and the exploration of what it could (eventually) evolve into, has only just begun. Feedback based on initial hands-on experiences was promising, especially as not all envisioned functionality had been implemented yet. Recognising this, the app needs further testing in a practical business environment to really optimise it for its intended function: to cater the needs of all designers, and allow them to select materials with low environmental impacts. Thereby making ecodesign accessible for the average designer, whether it be in a business or an academic setting.