It wouldn’t work with any sort of good quality machine. It would almost definitely sense the string and reject the coin. Even if it didn’t, i’m sure something inside would close over to prevent you from pulling it back out.

My theory is, if you’ve thought of it, they probably have too!

nope it just does not work i tried it in two sorts one the 50 p would not pull back out and the line broke like something had hold of it and the other it gone down and was rejected but i had a half a line attched and nothing to cut it with so had to run and leave half a line and 20p in the machine