This. Depending on the airport/airline, some of them will do it for you. For example, in the Bahamas, there is a kiosk (really just a clear container with a coin slot) at the bottom of a set of stairs in the departure area (or was it at the top...)

Cathay used to promote a change for good program on their planes.... Haven't seen it in a while but I haven't rode them in ages.., The FA's would provide you with a small paper envelope and you would dump your old coins there and they would forward it.

https://news.cathaypacific.com/chang...n-2017-203970#