Appropriate technology is widely recognized as a good solution in providing alternative technology for underdeveloped people who live in very limited circumstances. However, it is often seen as an idea without a clear explanation from an engineering perspective. One of the critical processes in the appropriate technology design process is materials selection. This study aims to provide applied logic for selecting materials in the design process. The logic is constructed by surveying previous notions from researchers. Reasoning techniques are explored by using design thinking. This study reveals that there are four focuses that must be applied to find sufficient materials for appropriate technology. This study also concludes that, unlike pure engineering efforts, which tend to substitute materials given in a technology design with locally available ones, appropriate technology starts from existing resources to produce its design. It requires soft selection by involving local people in exploring any potential materials which already available in their own area. By looking at previous studies which tended to ignore the contribution from local people in exploring potential materials, this study turns it back and encourages insights for further research around it.