A coinex is a remarkably simple machine. You put in change of one currency, and it spews back change in another - typically, sterling. The machine may accept many different currencies, although the need for this is lessened with the advent of the euro, but ultimately it can only return coins in one.
You might think this is boring. You'd be sadly mistaken. A coinex is a machine of such beauty and elegance that people in board ships frequently gather round to admire it, or so it seems to me. They are available on most P&O ferries, where travellers returning home can get a little compensation for the foreign coins they were otherwise unable to dispose of.
The exchange rate on them is quite shocking. Last time I used one, when the franc was still legal tender in France and the exchange rate was approximately £1 : 10FF, the coinex demanded 18 francs for a single pound. The reason for this is obvious; you have to cover the costs of the company exchanging all this coinage into useable currency. However, do not let this put you off using them. Coinexs can be fun for all the family.
I am currently attempting to purchase one on eBay.
I apologise if this write-up seems sarcastic. A coinex is a simple currency exchange machine, but I had to give it a little bit of soul.