How To Make Sprue Goo

How To Make Sprue Goo

What is Sprue Goo?

If you are into model building or 3D printing, you might have come across the term “sprue goo.” Sprue goo is a material used to fill and seal the gaps or imperfections between the different parts of a model before painting and finishing. It helps create a smooth surface by melting the plastic together, resulting in a flawless appearance.

Making Your Own Sprue Goo

While you can easily purchase sprue goo from hobby stores, making your own can save you some money and give you more control over the consistency. Here’s a simple step-by-step guide to making your own sprue goo:

Step 1: Gather Your Materials

To make sprue goo, you’ll need the following materials:

  • Plastic sprue or waste plastic from model kits
  • Plastic cement or polystyrene glue
  • An empty container with a lid
  • A stirring stick or spatula

Step 2: Prepare the Plastic

Begin by collecting plastic sprues or any waste plastic from model kits. These plastic parts are typically leftovers from cutting out parts on plastic model kits or support structures from 3D printing. You can also use melted down plastic sprues from previous projects.

Step 3: Break Down the Plastic

Using a sharp hobby knife or a pair of scissors, cut the plastic sprues or parts into smaller pieces. It’s easier to melt and mix the plastic when it is broken down into smaller chunks. Aim for pieces that are around 1-2 cm in length.

Step 4: Melt the Plastic

Now it’s time to melt the plastic pieces. Open a well-ventilated area or work near an open window to avoid inhaling any fumes. Take your empty container and place the plastic pieces inside. For safety, make sure your container is made of a heat-resistant material, like glass or metal.

Next, take your plastic cement or polystyrene glue and pour a small amount onto the plastic pieces. The glue acts as a solvent for the plastic, helping to melt it down and form a gooey consistency.

Step 5: Mix and Stir

Using a stirring stick or spatula, begin mixing the plastic and glue together. Stir the mixture continuously until the plastic starts to melt and blend with the glue. Keep stirring until you achieve a homogenous, gooey paste-like consistency.

Step 6: Let it Cool and Store

After achieving the desired consistency, let your sprue goo cool down for a few minutes. As it cools, it will become more solid, but still spreadable. Once cooled, transfer the sprue goo into a smaller container with a tight-fitting lid. This will help keep it fresh and prevent it from drying out.

Using Sprue Goo

Now that you have your sprue goo, you can start using it to fill gaps and imperfections in your models. Here’s how:

Step 1: Preparation

Clean the surfaces where you plan to apply the sprue goo. Remove any dust, oils, or debris that may interfere with adhesion. It’s also essential to ensure the surfaces are dry before you begin.

Step 2: Apply Sprue Goo

Using a small spatula or applicator, scoop a small amount of sprue goo from your container. Apply a thin layer to the gaps or imperfections you want to fill. Make sure to spread it evenly for a smooth finish.

Step 3: Let it Dry

Gently let the sprue goo dry for a few hours or follow the manufacturer’s recommendations. It typically dries within 1-2 hours, but some formulations may take longer. Avoid touching or disturbing the area as it dries to ensure a flawless finish.

Step 4: Sand and Finish

Once the sprue goo has completely dried, you can sand the area gently to make it smooth and seamless with the surrounding surface. You can also apply additional coats of sprue goo if needed, repeating the process until you achieve the desired result.

Step 5: Paint and Enjoy

Now that your model’s imperfections have been filled and smoothed, you can proceed with painting and finishing. Apply primer or base coat to the entire model, and then proceed with your desired paint and finishing techniques.


Making your own sprue goo is a cost-effective and straightforward solution to achieve flawless model finishes. By following these steps, you can create your own sprue goo and fill in gaps and imperfections with ease. With the right amount of patience and practice, you’ll be able to enhance the overall quality of your models and enjoy the satisfaction of a perfectly finished project.

Leave a Comment