A Universal Mug

This mug would succeed in terms of ergonomics research. It would score rather high in all categories, but lets consider the first one: safety.  When designing consumer products, safety is always a priority, no matter what the product may be. If it's safe, then it's more attractive to consumers, and is probably better and will probably last longer than something that is not as safe.
When people think of mugs, some people might think of ceramic mugs, some may think of coffee mugs, and others may think of travel mugs. This mug here, would probably be a travel mug and safety for a travel mug is definitely a concern.  This happen to be a concern that this mug tackles well.  The mug here is not made with ceramics, but rather, it's plastic.  Travel mugs usually have two different layers, but in this case, both layers are plastic--a thick kind of plastic.  Plastic works well for a travel mug because it doesn't absorb the heat, as does the ceramic mugs. Therefore, if people wanted to carry it around, they would not have to worry too much about burning their hands if they were to grab at it. In addition to that, there is a handle. So they have the option to hold the mug by the handle and not have to worry about holding something really hot at all. The option is theirs.  The lid is a pop on-pop off.  Initially, people might not think that the lid could effectively keep the liquid inside, but it actually does.  Once the lid is on, it secures the liquid inside almost like an airtight seal. Another safety precaution that mug displays is the phrase: CAUTION. Contents may be Very Hot.  Nothing can be more simple then simply stating the possibility that the mug can hold hot things inside.
As shown, a lot of thought was put into making sure the mug can be used and not potentially burn anybody that uses it.  The material used to make the mug, an optional handle, and a precautionary phrase all contributes to making sure the mug is safe to use!