Made from, made of, made by

When you are talking about the materials that are used to make something, you say that it is made of or made from those materials.

Use made from when the original materials have been completely changed and cannot be recognized. Paper is made from wood.

Use made of when the original materials have not been completely changed and you can still see them: a table made of wood.

Do not use made by when you are talking about the materials something is made from: a small purse made of leather (not a small purse made by leather). Made by is used to talk about the person or company that made something.
All the furniture in this room was made by my grandfather.