It seems odd that anyone would want to make 'canned string'.
It's not even strong enough to hold anything you tie it to. It looks like it has a similar consistency to that styrofoam stuff they use to pack things to send far away, but is actually much softer. This string substance is crammed into a can with a propellant gas so that when someone touches the pressure sensitive nozzle a slimy/rubbery 'string' shoots out and clings to any nearby surface within two feet (especially clothes). It comes in vivid colours and is usually used at parties.