I’m interested to know about your specificity of male elders regarding washing machines. Is it because you are assuming that male elders will be the primary users of the machine, or are you perhaps thinking about downstream impacts of such a system, such as pollution?
In general, washing machines are likely to be used by a variety of people and multiple perspectives should inform your design process to ensure it is appropriate for the community. I’ve answered another question in this forum about potential users of a washing machine alternative which I have linked below which you might find helpful in shaping your understanding.
Role of Indigenous women in local communities in Cape York