Metal Casting With SUGRU




About: Travelling since 2013. I'm currently in Australia for some reason. --- I’m Calvin Drews, and I love to learn, experiment, invent, create, repair, and generally just do things myself. A sort of modern jack o...


Please vote! vote! vote! vote! vote! Do it! :) (This is in a contest, you know! :D)

Make sure to check out my blog!

Not to long ago, I started my ventures into metal casting. My early molds were made of plaster, but I quickly learned that silicone epoxy makes GREAT metal casting molds. Unfortunately, the silicone epoxy I was using was not designed for casting metal, and was too soft and flexible. My early silicone molds were not tough enough for lots of repeated use.

But Sugru, on the other hand, is a very durable silicone mold making material. It makes molds just as good as the silicone epoxy I used previously, except Sugru is WAY more durable, and will make molds that will last dozens of casts.

The cast quality of this skull isn't quite exactly what I'm after, but I was in a hurry. Molds need to be broken in before they with make great casts, so the first, second, or even third castings may have bubbles or vacancies. The skull in the main picture is the second cast. You shoulda seen the first one ;)

Ok, this goes without saying (but I'll say it anyway)...
Casting metal involves the use of butane torches. Butane torches have fire. Fire can burn you. So can hot metal. Got it?

If you want to cast high temp metals, just use the sugru molds for wax, then use the lost wax casting process.

There are several people in the comments arguing about fumes. They have not actually done this instructable, so they wouldn't know. Anyway, if you use solid lead free solder, there will not be any fumes. I know this from experience. Please, though, trust your own judgement and use common sense!

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: What You'll Need

You will need:


-Object to make a mold of

-Mineral Oil

-Tin Solder (or lead*) Make sure it's not acid core. If you use acid core, you will generate      hazardous fumes.

-Butane Torch

-Something to melt the metal in. I use a piece are firebrick carved into a bowl shape. You  could make your own out of Plaster of Paris, or a copper pipe endcap. Do not use clay or  ceramic.

-Mad Skillz

That's it!

*If you use lead, please make sure you are aware of the hazards. The MSDS for lead can be found here.

Step 2: Making the Mold

Sugru is very sticky. You need it to release from the object you are molding, so oil the object in question. You'll only need a little bit of oil on the object, don't over do it and make it all drippy.

Gently mold the Sugru around the object; in this case, a small skull bead. Leave a little opening to poor the metal through (see picture two)

Put the new mold on a flat surface and let the it dry for 24 hours.

Step 3: Releasing the Object

Make an incision around the perimeter of the mold with an Xacto knife. Gently pull out the object, the Sugru could tear if you're rough... and that's something to avoid.

Once the object is released, piece the mold back together and hold it that way with a clamp (picture two)

Step 4: Casting the Skull

In my experience with casting metal in silicone, molds need to be broken in. Your first few casts will probably be failures, but the more you cast the better the mold gets.

Casting is pretty straightforward: Melt the solder with the butane torch in a crucible of some kind, and poor the molten metal into your mold.

After the metal is cool, you can unclamp and pull the cast of of the mold

Step 5: Results

Now I did this because I wanted to show you that metal casting in Sugru CAN be done. If I spent more time use the mold, then my results would have been even more accurate.

Take a look at the Buddha on the intro. I Cast that using this same method. The mold I used was just more used and very well broken in.

Here are the pictures of my results:

Sugru Contest

Runner Up in the
Sugru Contest

Be the First to Share


    • Made with Math Contest

      Made with Math Contest
    • Cardboard Speed Challenge

      Cardboard Speed Challenge
    • Multi-Discipline Contest

      Multi-Discipline Contest

    168 Discussions


    1 year ago

    After making the mold, I would recommend curing it at room temperature for at least 24 hours.

    If you're using a 2 piece mold and you don't have a vise clamp, put the two mold pieces together between 2 small wooden boards that have been sized to fit the side of each mold. Clamp them together with C-clamps. You could also use rubber bands.


    2 years ago

    Mary K.Newman

    This guide will demonstrate to you industry standards to make a modest and straightforward shape out of a silicone compound called Sugru. From this warmth safe shape one can make a Pewter throwing, for gems and such. In spite of the fact that an expert throwing will convey a more powerful and bigger shape, any reasonable person would agree for little, point by point 1-offs, I observed utilizing Sugru to be a basic and financially savvy strategy.


    3 years ago

    just starting out will sugru stand up to casting with



    3 years ago

    Does it work with wax (sculpting wax) or not


    4 years ago on Introduction

    Is there anyway that I could use some sort of magnetic material as I want to cast something with a magnetic metal. If so any suggestions as to which type of metal?

    2 replies

    4 years ago

    Would sugru withstand molten silver?


    4 years ago on Introduction

    I'm looking for a durable way to cast many Gallium items. Do you have any experience with using a Sugru mold for Gallium?

    1 reply

    Reply 4 years ago on Introduction

    gallium melt in your hand or at 30 c so the mold will by used for ever


    4 years ago

    I am wanting to try out casting, but would like to do it with metals of higher melting point. How hot can this handle?

    1 reply

    Reply 4 years ago

    If sugru is anything like Silicone, then it will be effective up to temperatures of around 300 degrees C, the best you can hope for would be Pewter or Lead. Make sure you cast in a well ventilated area though, metals can emit some nasty gases. Good Luck!


    5 years ago on Introduction

    I'm new to casting, as I'm wanting to test it out with my cosplay. Which would be a better idea to start out with? Epoxy or Sugru??

    1 reply

    4 years ago

    Just a tip pitting, the little bubbles and impurities that occur in the lead casting, can be minimized if you use first a mold cleaner first. I recommend micro mark, and secondly lightly!! Powdering your mold with talcum powder. Please use a respirator mask when working and good ventilation. I cast on regular basis and worked heavily with these materials in similar molds on some pieces for a show a few years ago. Good Luck!

    Also using old cans to try to cast is not worth the money you save, unless you want a casting with tons of impurities and pits also be willing to brave the cloud of toxic gasses you will be exposing yourself too.


    Reply 7 years ago on Introduction

    doesent tin have a higher melting point? so why does aluminum destroy it but not tin?