Delivery droids which wait patiently for a customer to try on garments before returning any that are unwanted or do not fit are being developed in the next futuristic leap for online shopping.

Amazon has published a series of sophisticated designs for self-driving “storage compartment vehicles” capable of delivering purchases to buyers by road, air and water.

Blueprints show Wall-E-like robots with caterpillar tracks, helicopter rotors or even submarine-style propellers to navigate any terrain, guided from a depot to the pick-up destination by GPS.

On arrival, the customer would open a locker with a smartphone code or facial-recognition to retrieve their orders.

After trying on clothes and shoes, they can choose which to keep, placing unwanted items back in the locker and sending the droid away.

The designs, in a US patent, are intended to combat the inconvenience of waiting in for the collection of returns, or having to post them. It would also reduce pollution, requiring one trip instead of two.

The patent says the customer could order from a website “two pairs of shoes, each having a different size and select the items for delivery. The ordered items ... may be stored in … the storage compartment vehicle and made available to the customer at a delivery location.”

They may then “try the ordered items on to determine which item the customer desires to keep, and return the other item into a storage compartment”.

It is proposed that they would scan the shoes they do not want for a refund, before the robot takes this pair back to the warehouse. The transaction could be overseen by a “human agent” viewing a livestream at Amazon’s warehouse, enabling real-time chat.

Amazon says patent filings “do not necessarily reflect current developments to products and services”.

An Amazon spokeswoman added: “Like many companies, we file a number of forward-looking patent applications that explore the full possibilities of new technology.”