Bello reusable ice cubes are available in packs of 18 for a small sum from various places: I got these from Amazon, but various web-shops and large out-of-town giant-box shops stock them.
These are basically soft plastic cubes partially filled with water. To use them, you put them in the freezer, and the water freezes, filling the cube and giving you a piece of ice sealed in a thin plastic layer.
Now, you might reasonably inquire why I would be excited about such a thing. They’re a reasonably practical way of cooling a drink, and have an advantage over simply using ice in that they don’t dilute your drink with water as they melt. If left out by mistake they’re easier to clean up than ice, meaning that clumsy people will be less likely to have to deal with a puddle (unless they are damaged, and therefore leak). I’m certainly going to make use of these for keeping drinks and food cool, given how insanely hot it is in South West England this summer.
My reason for being excited by these cubes is far nerdier, however — they allow me to set-up photos like this: