Where can you find inspiration for design ideas? Patents!
These pages have some tips and tricks for searching patents -- which is a tricky exercise because:
Most patents protect a function rather than an application -- such as, an extruder rather than a device for making donuts or drinking straws.
Many large and complex products are governed by multiple patents developed over time by different inventors.
Some inventors (and their patent attorneys) deliberately use obscure language to hide their intentions until a product is released.
Many patents do not contain the product, brand, or trade name. They may be trying to hide, or they may not have devised the product name at the time of the patent application.
Some products (such as the recipe for Coca-Cola) are not patented, often because the inventor does not want the secrets to be published.