How-To: Simple Molding and Casting for Toy Duplication

Craft & Design Fun & Games
How-To: Simple Molding and Casting for Toy Duplication
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Super Awesome Sylvia is back with another Mini Maker Show, this time it’s all about casting!

Did you ever want another of your favorite action figures? Or maybe you want to try something crazy with a toy but didn’t want to ruin it? Well today we’ll show you one super awesome way to clone your own toys with simple Molding and Casting for Toy Duplication! Lets Go!

For this build we’ll be using:

  • Some toys to be copied (we explain how to pick one below)
  • Pliable Molding material (We’re using ComposiMold, because it’s easy and reusable.)
  • Disposable cups or mixing containers, big enough to fit your toys
  • Casting Material (we’ll be using polyester resin for fiber-glassing from the hardware store)
  • A small spray bottle with a mild solution of white PVA glue and water (to prevent bubbles)
  • and finally some mold release (We’re using non-stick cooking spray)

Not every toy can be duplicated easily. Toys with big holes, hook shapes or moving parts won’t come out of your mold properly, and toys that don’t have a good way to pour in your casting material just won’t work at all without adding sprues or making multiple molds. Almost anything can be copied using molding and casting, but complicated toys and objects require a bit more work, and for this build we’ll just be covering the basics.

It helps to think about your toy as a funny shaped pipe, or balloon. Once the ComposiMold has been poured and your toy removed, you’ll have to use one of its outer edges as a hole to fill up every part of it quickly during casting. Also, without a way for air to escape during molding or casting, you’ll be left with problem causing air bubbles, and without good shapes or entry points, duplicating your toy gets a lot trickier. Be sure and pick a toy with a large base or flat side that will be the area to pour into, and try to think about how you’re going to remove it from the mold without hurting the toy or the mold. If you’re not sure, experiment! One of the greatest things about ComposiMold is that it’s reusable. If your mold fails miserably, just remove your toy, take it apart and it’s ready to be melted and poured again and again!

If the toy you picked out is plastic, there’s a good chance it will float in the molding material, so you’ll need to hot glue it to the bottom of your container. Make sure it doesn’t touch the sides! If your toy is molded too close to the side of the container, the molding material will be too thin to properly support your casting.

One last step before pouring, spray the glue and water mixture on your toy, rub it in then pat it dry. Now we heat our ComposiMold in the microwave until it’s nice and smooth, and carefully pour it into the cup. Drizzle your molding material carefully and slowly around your toy, making sure to let every crevice fill evenly without bubbles. Once you’re done, set your molds to cool in a safe place (or the freezer if you’re impatient!). When your mold has cooled, remove the cup and carefully cut down the side of the mold from the base to make your parting line. Don’t go all the way, we just need to open the mold up enough to remove the toy then put it back together to make our casting. Having as few parting lines is preferable as there will be less flashing to remove, and less chance of the mold becoming misaligned.

Now add a little cooking spray inside of the mold with a cloth or cotton swab to ensure your cast won’t stick, then close it back up with a little tape to keep it from leaking. Now we’re ready to mix our casting material, but how much to we need? Take a measuring cup and fill it to a known measure line, then take your toy, and completely submerge it. The amount of change is the volume of your toy! Fill a disposable cup with this amount of water (plus a little more for drips or messups) then mark the line. A perfect measure means no waste!

Now we head out to a well ventilated area to mix our casting material. Polyester resin is smelly, flammable and a skin irritant, so wear gloves, and don’t breathe the fumes!

After filling the cup, carefully mix in the right amount of hardener (it’s different for different resins, follow your directions), then slowly drizzle it into your mold. Be sure and squeeze or bump the mold a little to make sure no bubbles are caught. Let this cure for a few hours, and when you come back, you just might have your very own toy clone!


Molding and casting can be pretty complicated, and in the words of my favorite mold maker and MythBuster Adam Savage, “Failure is always an option”. Our failure this time happened to be that the thin walls of our Bumblebee mold melted from the exothermic reaction of the resin hardening, luckily not before the ComposiMold did its job! Bubbles and bad pours are most common, and will get easier to avoid with practice. Once you’re done with your casting, you can sand and paint your resin, or reuse your molds and try other casting compounds like plaster, clear resin, wax, rubber, concrete or even chocolate (with food safe ComposiMold)! The world is yours to clone!

Remember to experiment, stay safe, and get out there and make something!

12 thoughts on “How-To: Simple Molding and Casting for Toy Duplication

  1. migpics says:

    I want one of those Super Sylvia finger pointer things so I can use it at work when I’m pointing at things on my screen.
    Uh Super Sylvia, where did you get that at?

  2. Digital Photography Fan says:

    Can’t wait to try this…Thanks!!

  3. Anonymous says:

    Hi Sylvia im jayden i realy like you because you are just like me and i thought i was the only kid that would watch mysthbusters and i luuuuuuuuuv making stuff how old are you

  4. Anonymous says:

    hi Sylvia im jayden an 11-12 year old boy i realy like you ………. you are so smart i always had a passion for building and i think well be best internet friends you are like my soulmate friend How old are u

  5. Elliot Wilson says:

    I really want to make spaceships, like the Pool ship from Animorphs or the Blade ship. How would I do that?

  6. steffy says:

    very nice tips to make a molded toy by using rubber molding you post a proper procedure. great to see this thank you:)

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Becky Stern is a Content Creator at Autodesk/Instructables, and part time faculty at New York’s School of Visual Arts Products of Design grad program. Making and sharing are her two biggest passions, and she's created hundreds of free online DIY tutorials and videos, mostly about technology and its intersection with crafts. Find her @bekathwia on YouTube/Twitter/Instagram.

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