I seriously took 2 minutes to prepare. I have just dumped a magnet basket on a tray and popped 3D cards.
Here is a quick link to free 3D shapes word cards from Twinkl
Polygon - a shape that has the same number of corners and sides. Also known as a zigzag line that is closed.
You can use any materials you have at home to build it. I used playdough and cut up straws, but toothpicks and playdough or small marshmallows work as good.