The countryside is littered with shopping trolleys, dragged there by shoppers, vagrants and yobs. The whole process of shopping with these things is a nightmare anyway, for store owners and shoppers alike.
Until someone invents home delivery (!) and all those ugly supermarkets close in favour of underground warehouses, I thought it might be interesting to consider the global proliferation of trolleys problem. Here is an alternative to the coin-in-the-trolley deposit approach (since I can never remember to bring the right coin with me anyway).
Ice. Imagine a trolley which can be as large or small as your purchases require and which, when you have used it, just disappears. So why not just make the entire basket thing of ice? Answer: the cost is way too high…if we just reproduced existing designs, I reckon it would require removal of 4 MJ to cool water enough to generate a solid trolley in the existing design. So my suggestion would be to come up with a trolley ice mould which is sufficiently strong in design to carry the shopping, whilst minimising the material. Surely someone out there with a CAD system and some polymer engineering expertise could cut the required mass of ice by a factor of 10…or 100?
Maybe there’s a way to make a shell-like design which could be sprayed onto a standard former (ie fast) and still be sufficiently light and strong? It would have to run on detachable, ablative skids I guess, but at least the shopping would get home still chilled and you could have separate baskets which exactly fit your own car boot.