Playful Objects -3D Prints, Castings, and Empty Vacuum-formed Packaging

This project uses discarded vacuum-formed packaging as molds for playful concrete castings. Custom 3D-printed parts attach to each casting, forming quirky, robot-like figures.

By combining digital fabrication with traditional casting techniques, it repurposes waste materials into charming, contemporary compositions.

|| Material List per Casting

|| Casting material:

choose based on desired properties and application. Options include concrete, resin, plaster, plastic, or wax.

Quantity should be calculated according to the manufacturer’s instructions and the size of the vacuum forming mold used.

|| Vacuum forming packaging (mold):

1 unit per casting, collected and chosen by the user based on availability and size.

|| 3D printed parts:

Select the desired parts from the provided files (e.g., legs, arms, connectors) to create your own figure.

|| Sharp object:

something suitable for making a hole matching the diameter of the rod (e.g., awl or punch).

|| Transparent sheet (plastic or PVC) matching mold size:

1 unit (optional) used to ensure a smooth, even top surface of the casting, but not mandatory.

|| Clips or clamps to secure the sheet to the mold: 4-6 units per casting (depending on mold size).

Step 1: Collect Empty Vacuum-formed Packages

Look for discarded vacuum-formed packaging in your home, local shops, or recycling bins. Choose pieces that are clean, structurally intact, and have an interesting cavity shape. These will serve as your molds for casting.

Tip: Transparent or semi-transparent packages make it easier to see the casting process and control surface quality.

Download the provided STL files for the parts you’d like to include — arms, legs, connectors, or other elements. Use a 3D printer to print them in a material suitable for your casting process (e.g., PLA, PETG).

Important note about each part:

For every element you'd like to include — such as an arm, leg, or hat — you need to 3D print a matching insert. This insert is embedded into the mold before casting.

Each insert should be paired with a locking ring that prevents it from being pulled out once the casting has hardened.

The file names will help you match each insert with its corresponding part and locking ring.

a | Use a sharp object ( like a sewing needle or a round file) to carefully punch holes in the vacuum-formed mold where you want to insert the connectors.

b | Insert the 3D-printed connector parts into the holes. If the hole is too wide or loose, you can seal the gap with plasticine to keep everything in place.

c | Before casting, it’s best to insert only the rods or connectors — without attaching the legs or arms yet. (Tip: In the photo shown here, the limbs are already attached, but I’ve learned from experience that it’s better to add them only after the casting is done.)

d | To prevent the rods from sliding or being pulled out during casting, attach the printed rings onto the rods from the outside. This helps anchor them securely in place.

e | Optionally, if you want a smooth, even surface on top of your casting, you can cut a transparent sheet (like PVC) to the size of your mold and clip it on using 4–6 clamps. (This step is not mandatory, but can improve the final finish.)

a | Prepare your casting material according to the manufacturer's instructions. This can be concrete, plaster, resin, or any other material of your choice.

b | Slowly pour the material into the mold, making sure it flows around the connectors and fills all the cavities.

c | Tap the mold gently or shake it slightly to release any air bubbles trapped inside.

d | If you're using a transparent sheet to flatten the top surface, this is the time to clip it in place and press gently for an even result.

e | Let the casting cure fully before moving on to the next step. Drying time depends on the material used.

a | Once the casting is fully dry, carefully remove it from the vacuum-formed mold

b | If you haven’t attached the limbs yet, now is the time to connect them to the embedded rods or connectors.

c | If parts feel loose or wobbly, you can secure them using a drop of superglue (cyanoacrylate) to hold everything in place.

d | Rotate, swap, or mix parts to discover new figures and compositions — each result can be unique and surprising!

You’ve just brought a group of strange and wonderful robots to life using discarded packaging, simple casting, and a few 3D-printed parts. Each figure has its own character and unexpected charm.

Photograph your creations, name them if you’d like, and share them with the open DIY community. there’s a lot of joy in seeing what others come up with using the same method.

I’m curious to see how this method could work with softer materials, like rubber, or with different types of connectors, it could be an interesting direction to explore.