The Industry 4.0 era has resulted in several opportunities and challenges for the manufacturing industry and for small and medium-sized enterprises (SME); technologies such as the Internet of Things (IoT), Virtual Reality (VR) or Cloud Computing are changing business structures in profound ways. A literature review shows that most large-sized enterprises have rolled out investment plans, some of which are reviewed during this research and show that Industry 4.0 investments in such companies exceed the turnover of SMEs in all cases (<€50 million), which makes access to those technologies by SMEs very difficult. The research has also identified two gaps: firstly, the recent literature review fails to address the implementation of Industry 4.0 technologies in SMEs from a practical viewpoint; secondly, the few existing roadmaps for the implementation of Industry 4.0 lack a focus on SMEs. Furthermore, SMEs do not have the resources to select suitable technologies or create the right strategy, and they do not have the means to be fully supported by consultancies. To this end, a simple six-step roadmap is proposed that includes real implementations of Industry 4.0 in SMEs. Our results show that implementing Industry 4.0 solutions following the proposed roadmap helps SMEs to select appropriate technologies. In addition, the practical examples shown across this work demonstrate that SMEs can access several Industry 4.0 technologies with low-cost investments.