Central Saint Martins post-graduate student Mi Zhou has created toiletry bottles called Soapack that are cast from soap and melt away once they are no longer useful.

To make each Soapack, vegetable oil-based soap is dyed using pigments from minerals, plants and flowers and formed in a mould, in a process similar to slip-casting ceramics.

A thin layer of beeswax is used to line the bottles to make them waterproof, and prevent the liquid contents from dissolving the bottles before they are used up.

Users can keep Soapack bottles in a dry place to preserve them, or rest them on a soap dish and allow them to melt away on contact with water and with use.

"It is designed to invite the user to use it or even deconstruct it and make it eventually disappear," Zhou told Dezeen.

The project is a response to the disposable nature of regular plastic packaging for toiletries.

"Product packaging has always been thrown away, no matter how well-designed or what material it is made of," said Zhou. "I want to re-evaluate what packaging could be as well as help us to reduce our plastic footprint."

A standard plastic bottle can take up to 450 years to break down, and non-recycled plastic often ends up polluting the ocean.

Having seen edible packaging made for food, Zhou applied the same logic to shampoo and other personal care products.

"As a designer, I want to rethink the current mode of producing and consuming of these products and also critique disposable package materials."

With their delicate stoppers Soapack containers reference perfume bottles, a type of non-plastic packaging that people are less likely to treat as disposable.

"I found that compared to shampoo bottles, we are more likely to keep perfume bottles which mostly are made of glass and look gorgeous," said Zhou.

"Even if the perfume is used up, we keep the bottles since they are too beautiful to be discarded."

Making Soapack beautiful, as well as useful and sustainable, was a vital part of the project.

"We are living in a period of transition where we are encouraged to act 'sustainably', in situations where there are few successful options provided," said Zhou.

"We do need to encourage people to use alternatives to respect our environment better but not compromising in user experience."

If the user keeps them dry then Soapack can be kept as a permanent ornament, although it is designed to ultimately melt away to nothing.

"There are no rules, people can use and place it as their preference," said Zhou.

Traditional plastic requires fossil fuels to make and often ends up polluting the environment, so designers are increasingly coming up with more sustainable solutions, including packaging made from bacteria, bioplastic wrappers made from meat, and bags made from algae.

Photography is by Tom Mannion and Xinjia Zhou.