Shoes lined with elastic can be a source of much discomfort before they are broken in. The elastic can take a long time to stretch, causing blisters and sore feet in the meantime. To speed up the process, use ice to stretch elastic in shoes, making footwear wearable and true-to-size in a timely fashion.
Fill the two sandwich bags halfway full of water.
Seal the bags tightly.
Set one bag in each shoe. Position the bags so that they're pressing against the elastic.
Place the shoes in a freezer. Leave them there until the water turns to ice, which could take between 4 and 8 hours.
Remove the shoes from the freezer and remove the bags of ice from the shoes.
Try the shoes on. Walk around in them for 1 minute. If the shoes have not stretched sufficiently, place the ice back in to the shoes and leave them in the freezer for another hour.