This final graduation project is done at Handicare Bathroom Safety BV at Pijnacker. Like their name says, they are a manufacturer of safety products in and around the toilet-, shower- and bath environment. These products have a good balance between comfort, safety and design. With 70 years of experience, they are considered specialists in this field all over the world. For this project the main aim is to design a next generation shower seat for the product portfolio of Handicare; LinidoSolutions. The shower seat must be applicable all over the world, therefore apart from the Dutch market, the United Kingdom and Southern Europe (Spain) is taken into account. The “old” shower seat as it is now provides support in a seated posture while showering. Based on the needs of the user, this seat is also foldable and available with/or without backrest and armrests. This seat was introduced in 2003 and was one of the first shower seats produced entirely out of plastic. This has great benefits for the design, ergonomics, costs and production. Nevertheless, feedback has shown frequently arising problems in production methods and procedures. One of the main concerns of this seat is premature tumbling of the seat surface and fractures near the mount and its connections. The folding mechanism is unreliable and the connection is not solid and strong enough for all situations e.g. a transfer from wheelchair is very critical. This results in a large amount of complaints. With the next generation shower seat these problems have to be resolved. Further research shows that users have specific needs and requirements while showering on a shower seat. This has resulted in several project directions whereof the most promising direction is chosen. From the user research it shows that standing up, cleaning of the buttocks area, cleaning of the lower legs/feet and a transfer from wheelchair to seat is very hard to accomplish. This has to do with the disabilities of these users. Based on the chosen target group, the project direction “improvement of the buttocks area” is chosen. Research shows that cleaning of the buttocks area is not possible and very hard in a seated posture. Users have to stand up to properly clean this area. However standing up is an intensive activity for these people. Current products provide hygiene openings, but are still not optimal and very uncomfortable to sit on. From this perspective the main target group is chosen, which is based on the mobility classification of the user. The user can be divided into five categories; scaled from group A with the most mobile people to group E with the lowest degree of mobility. Target group B is chosen as the main target group for the shower seat. This group can be characterized on performing their daily activities in combination with a little help. This help can be provided by a walking aid and/or home care. This group often uses a shower seat, because they are not able to stand for longer periods of time or have an unstable posture. From this perspective the hypothesis of the final researches is defined: the smaller the seat surface, the larger the accessibility will be”. This means that a user can get enough support by providing a seat surface around the sit bones. Because of this principle an opening is made in the back and front. By supporting the sit bones a better and stable posture is provided, which can increases the comfort and based on this hypothesis two researches are accomplished. First the minimum seat surface is determined and these dimensions are evaluated according to access around the buttocks. Based on the hypothesis three dimensions can be determined: the opening between the sit bones, the length around the sit bones and the width of the seat. The first research elaborates on the minimum dimensions that are necessary to provide a stable and safe posture. 24 Participants evaluate different models and eventually the minimum dimensions are defined. During this research differences between gender and active and passive postures are noticed. Some of these aspects are of great influence to the final dimensions. The passive posture is defining for the length around the sit bones and the active posture in combination with male participants for defining the maximum opening. With the results of the first researches, ideas and sub-solutions are generated to improve the accessibility around the buttocks. On top of this, product improvement is considered. Five focus points are taken into account: the seat surface (improvement of accessibility), the folding construction, height adjustment, forces on the wall and the mounting construction. Eventually this leads to three concept proposals. In cooperation with Handicare the most promising concept is chosen. The final research elaborates on the accessibility of the chosen concept and the defined minimum dimensions. In this research the accessibility around the buttocks, private parts and legs is evaluated. This research shows a significant improvement of accessibility. Most improved is the access of the private parts, participant are very enthusiastic about the hygiene opening in the front. Furthermore, the accessibility of the buttocks area has been improved as well. Although, further research must prove that the opening in the back significantly improves the access of the buttocks for actual end-users as well. Nevertheless, this first research shows potential for implementation in the final design and has great potential in comparison with competitive products. Based on the last research, BILLY is developed and is now the next generation shower seat of Handicare. BILLY is a combination of a regular seat combined with the ease of a hygiene opening. Because the user is now supported on the sit bones, he no longer experiences the hygiene opening as uncomfortable, but enjoys the full range of its conveniences. Furthermore, an extra hygiene opening for private parts is included, which increases the accessibility even more. From this final design a prototype is made to eventually evaluate the product in an actual user context.