I needed big cartoonish shoes for a costume so I went to several party stores and costume shops looking for clown shoes. Everything I found was either more than I wanted to spend or looked awful, so I decided to make my own entirely from things I had at home and found in the trash.
Foam insulation – I found some in the trash. Since you won’t need very much, you should have no trouble finding it discarded from renovation projects or construction sites. You could also buy it from a hardware store.