There are toy and industrial design firms you can hire to take your concept from idea to prototype and even shepherd it through production.
If you want to do it alone you'll need simultaneous knowledge in electronics, mechatronics, mechanical engineering, design-for-manufacturing, parts purchasing, and procurement. That's before you build your product in a factory, or if you choose to do it yourself.
Simone Giertz is an incredibly smart and talented person with a lot of this knowledge, and even she will tell you how hard this can be.