In the raders of the lost ark free play in the first level be wille and activate the extra artifact magnet and as you come across the third artifact you will see a window. use willes scream and break the glass and grab it

If you want to get the key for the artifact room, you will need to get some characters to collect all 5 chests. Here are the list of where the chests are hidden.

In Glass.
On the shelf above the Thuggee monkey.
Behind the metal round bricks.
Behind the wall beside the hieroglyphics.
On the shelf above the table.

You will need:

A character with a rocket launcher.
A small character.
A thuggee character.
A female.
A character with a book.

When you have placed all 5 chests in the center of the room, start building it and it will make a crate. Then, punch it and it will reveal a key. Go to the Artifact Room and go to where the diamond stands, put the key in, and you can change the beam on any finished artifact.