Wax and plaster mold making in our weekend Molding and Casting workshop.

Before we jump into it, let’s talk a little bit about what exactly molding and casting means, and what the difference is between a mold and a cast. A mold is a hollow container that you can pour liquid materials into to form them into a specific shape. One really common place you may have seen molds used in the kitchen! When making a cake, for example, the pan that you pour the liquid cake batter into is a mold that will help shape the cake. When you pop the baked cake out of the pan, it will continue to hold the shape of the pan (the mold) because the cake is a cast of that pan. A cast is an exact replica of an object created using a mold and some kind of liquid material. Can you think of any molds or casts that you’ve seen or used before?

For this project, we’re going to be using clear packing tape to create casts of household objects, or even our own body parts!

You’re going to need:

  • Clear packing tape.
  • Clear cling wrap.
  • Scissors (if you plan on casting parts of your own body, we highly recommend using a pair of safety scissors like this. This will help you stay safe when removing the cast you create.)

To start, decide what you’re going to be creating a cast of. In the pictures in this post, we created a cast of a water bottle. You can cast all kinds of objects around your house, or even parts of your own body.

The first step in creating your cast will be wrapping your object in cling wrap. You will want to cover all the surfaces of your object or body part in cling wrap. As you go, make sure to be pressing the cling wrap layers firmly against your object. Be careful if you’re wrapping a body part. You want to make sure that you don’t wrap so tightly that you cut off circulation. Think about keeping about a fingers worth of space between your wrap layers, and your body.

Once the item you’re casting is fully covered in cling wrap, it’s time to add tape. The cling wrap will help protect the object from the tape sticking to it, and the tape will act as a hard outer layer for our cast, keeping it strong and rigid. Just like you did with the cling wrap, start wrapping your entire object in the tape, pushing it down into the cling wrap layers as you go. Make sure that every surface, nook, and cranny of your object being cast gets tape on it. You should aim for 3 – 5 layers of tape depending on the size of your object. In the end, you will want to have a nice solid shell of tape wrapped around your object.

As the last step in this project, you’re going to use the scissors to free you cast object from inside the cast you’ve created. If we go back to the idea of molds and casts, the item you’re removing is the mold for the cast you’ve just created out of tape and cling wrap. Using the scissors and starting at the bottom of your object, carefully cut a slit into your cast. The size of the slit you create will vary based on the object you’ve cast. You will need to slide your mold out from inside your cast, so keep this in mind while cutting your slit.

If you’ve cast your body part, this is where the EMT safety scissors can be very helpful. They have a dull end that can safely press against your skin as you cut. If you are not using these, be extra careful when cutting the cast of your body OR have a buddy help with this step.

When your slit is the correct size, carefully spread the edges apart, and slide your molded object out from inside your cast. Using a few more pieces of packing tape, reseal the slit you’ve created so that you have a solid object, with nothing inside. Once you’ve resealed your object, you will have an awesome rigid cast of whatever object you started with!

This project is an excellent introduction to the art of molding and casting, but there is so much more to explore! Share the exciting tape casts you create, or any other molding and casting that you do with us by tagging @nysci on social media.