There’s two Sydney makerspaces that Google tells me about; Robots & Dinosaurs in Meadowbank, and Makerspace & Co in Marrickville. I’ve never been to either, but they would certainly have the tools and experience to do what you ask.
If you’ve a disability that makes it difficult to access these places, you might also try the Technical Aid to the Disabled volunteer engineering team. When I was a member of that team we did some fascinating work for people. They are in Northmead at the moment. You might also access this team formally through a physiotherapist.