Picture of World's easiest silicone mold.
Yep. That's right. I am about to change your mold-making technique forever. This simple way of silicone mold-making will have you wanting to make casts of all your trinkets and toys.

You will need:
  • water
  • blue dish-soap (any brand seems to work)
  • 100% Silicone (do not buy quick set silicone, you need 100% silicone)
  • bowl
  • caulking gun
  • something you want to make a mold of.
  • scissors/knife
  • masking tape - to patch holes in your positive, if necessary.
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Step 1: Make your catalyzing solution.

Picture of Make your catalyzing solution.
By mixing a high-concentration of dish soap with water in a bowl, one is actually making a catalytic bath for your silicone. The glycerine in the dish soap accelerates the cure process for of your 100% pure silicone.

This is by no means an exact science, I use blue dish soap because it allows me to see how much I have added to a water bath, I approximate that I used 4 oz. of soap in 64 oz. of water.

Step 2: Catalyzing the silicone.

Picture of Catalyzing the silicone.
Cut off the tip of the silicone caulk tube, and set it in the caulking gun. Unload enough silicone to surround the desired object, into the bath.

I use the whole tube usually.

Step 3: Preparing the silicone.

Picture of Preparing the silicone.
While keeping your hand submerged in the dish-soap catalyzing bath, gently clump the string of silicone together. Form it into a ball, and slowly massage it. Fold it, stretch it out, and work it very much like one would knead dough.

When it begins to become a bit less malleable, and stiffen, it is time to sink your positive into your material. In this case, Mike helped me, and we used his dinosaur, Jesus. (hay-zoos)
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Polinom1006 months ago

Can you cast metal in this silicon mold?


audreyobscura (author)  Polinom1006 months ago

I've never tried! Maybe low melting point metals like pewter

Cube_8 months ago

This doesn't seem feasible for larger projects, how dissapointing. (I'm make various custom things and decided I want to make two custom electric guitars for myself, one out of wood and another out of either fiberglass and resin or carbon fiber and resin (with a custom airbrushed paintjob) and a silicon mold seems the best option for this (since the resin one will be the same design as the wooden one)(
Any suggestions for how to make a silicone mold for large objects?

equal parts cornstarch and silicone using baby oil to mix it well into a paste them spread it over your item that you want to mold. it cures quickly so work fast

I wouldn't recomand it for large items. Silicon is quite expensive, the fumes are very strongs and you need to work very quickly. Once you set the first mold you won't be able to add a second one.

Ooo, handy tip: thanks!

audreyobscura (author)  Cube_8 months ago
Hey there! I have used this technique to cast larger objects....sort of.

My methodology is to make cardboard, or coroplast negative molds, and then coat them with silicone. The Silicone doesn't machine all that well, but I have found that cake decorating tools are the best for spreading it, and making even layers.


that's really not feasible for my projects, I was hoping I could just build a square of wood and put the object in it and pour silicone over it (once it solidifies I could just flip it over and pry the object out)
My workflow will require the additional structural integrity to make sure the mold doesn't deform too much while I apply carbon fiber and resin (causes air bubbles and looks bad, sometimes it cracks altogether)
Further I'd prefer if the mold was re-usable

Any idea how I could achieve this? I tried googling it but apparently most people don't cast very large objects

The Rambler Cube_7 months ago

If you look into costume and prop making I think you'll find some pretty decent sized items being cast. The silicone of choice tends to be a Smooth-On product. I haven't personally used it, as it is a bit expensive to just play around with and I haven't needed it for anything that justified the expense, but everyone who uses it swears by it.

Cube_ The Rambler7 months ago

Oh? This seems to be what I need actually
"Project Specific - Smooth-On's wide range includes mold rubbers that can be poured on , brushed on , sprayed on or pressed on to any original sculpture and will reproduce detail perfectly. Reproductions can be cast in urethane plastic, epoxy resin, plaster, concrete, and more."
thanks ^^

The Rambler Cube_7 months ago

No problem.

Pompom14 days ago

Does the temp of the water matter?

Pompom Pompom13 days ago

It seems as though you don't want it too warm I've cool room temp. Yup, answering my own question.

simonsch14 days ago

Great post! I have used this mould making technique many times so I thought I would contribute a few tips of my own. Acetic cure silicone will cure much faster that neutral cure. for speedy results use acetic cure. I would recommend a coating of soap on the hands before plunging them into the water/soap mix as the silicone can still be a bit sticky even in the soapy water. Also too much soap in the water can cause the silicone to become lumpy and not consistent. This water curing technique can also be used for direct modelling of silicone sculptures.(see photo) I usually make the sculpture in small parts and then join them together at the end. Silicone can easily be coloured for this by adding oil paint. For those commenters wanting a two part mold using this technique, build a clay barrier to seperate the halves, same as all two part mould making, and a good wax based release between the silicone halves so they don't stick together. Cheers, great instructable.

Pompom14 days ago

Why use 100% silicone caulk? What happens if you use latex caulk, or latex acrylic plus silicone caulk? If using for cold process soap making, would anything other than silicone produce an undesired outcome?

Also, I would like to create a mold of a fancy soap I was gifted. Can I do this? Or will the wet silicone clay cause the soap to dissolve some? The soap is over a decade old, so it's had time to dry out a bit but still look just as pretty.

Finally, could spray foam be used, specifically for CP soap? Or would there be potential for chemical reaction?

Thanks for any help.

ponyboy198123 days ago
I'm kinda freaking out I did the the steps and used 100% silicone and my molds are pasty? Help!
CementTruck1 month ago

Is there a reason why you don't just cut the front of the tube off and push a rod through the backside and dump the whole contents out in one fell swoop? Does the "spaghetti effect" help in some way?

I want to do a heat resistant silicone. My kids have a really old crayon maker whose molds have disintegrated over time but the rest of the machine still works well.

save3141 month ago
Hi is it possible to une sillicone casting in the silicone mold? Will it fuse together or I will be able to remove my sillicone final piece from the silicone mold?

Silicone will stick to silicone - I personally would not recommend it. If you have the time to play around with it, you could TRY it using a mold release spray as a barrier but even with a heavy coating of mold release, I've still had issues with old and new silicone fusing together..

SaintAstra10 months ago

So I tried this and finally succeeded - right silicone, dish soap. The mold came out nice (any imperfections were my own fault) and it even dried within a few hours. I made two molds. I poured my resin and when I popped the piece out, it was eaten away and tacky, like the surface of the moon only a lot grosser. It wasn't cured all the way and the parts that had touched silicone felt like melted gummy bears. It reeked of vinegar (No idea why, since vinegar went nowhere near this project). The inside of the mold had resin residue, all tacky.

I waited a full day, washed the second mold out thoroughly, thinking maybe the dish soap reacted or it was a bad batch of resin. Nope - tried it again, this time put half in the silicone mold and half in another plastic mold for control. Resin cured fine in the plastic but was still eaten away and tacky in the silicone mold. Not just in the cavity - I put a drop on the flat part of the mold, and that won't even come off it's so tacky. I have absolutely no clue why this happened.

I used:
GE Silicone I 100% Silicone for the caulk (tried it with II and it was a noxious failure)
Dawn dish soap
Wilton Liquid Glycerin
EasyCast Epoxy Resin
Tap Water

100% silicone does smell like vinegar until it's cured and silicone
cures on the outside before it cures on the inside and can actually take
days or weeks without some sort of catalyst, which soap is not. Water,
on the other hand, is, and that's why you can handle the silicone in a
water bath, because the outside surface is basically cured but,
otherwise, that doesn't do you any good because the uncured bits are
inside, sealed and covered in cured bits.

Cornstarch or pure talc
will allow curing from the inside out, but the process would be
different. You can search "Oogoo" on instructables or youtube

All the soap does is keep it from sticking
to your hands and the container. You might also be able to use it as a
mold release by dipping your item in soapy water before you stick it in
the mold. Which would also preclude leaving the item in there while it
cured, because the wetness of the item would cure the silicone that
touched it. You COULD drop the mold with the item into your soapy water
for a few minutes and then de-mold the item and set the mold aside to
cure for a few days.

If you want a "right now" mold, I'd definitely use oogoo.
You're not going to get a very detailed mold using it this way as the
outside of your blob is water cured into its blob shape and when you
unmold it, there's going to be some rebound because while silicone will
stretch, it will also want to bounce back to its original shape so you'd
have layers beneath the surface in the shape of your item and pulling
one way, while the preformed blob shape is pulling the other way -
hence, distortion. Even so, it is sort of cute, in a rough,
impressionistic way.

I use resin to make jewelry, and it sounds to me like you need to try a new resin. It doesn't sound like the resin is setting right, which has nothing to do with the mold. I would try a different resin mix. Could it be there is something wrong with your product- too old, not mixed right by the company? Good luck in the future.


i dont think that is a normal occurrence maybe get it checked out. depending on the kind of silicon you used it could have dried to youre hands and that is what you saw

LaurenSHayes2 months ago

Hhhmmm...I wonder if you could use this method to make a mold of a bowl? I'm trying to make an inexpensive mold to make a resin bowl. Any ideas?

Nice Instructable, but too bad the image is consciously misleading: the mold is not closed, the created figure is nothing but similar to the real object since the back is completely inexistant.

Not liking the $20 - $60 price tags on silicone molds I just tried this! Cost me about $4.69 to make two and they seem to be just as good as the one I bought recently! Thanks!

mysterymayhem4 months ago

tried today, used white silicon and some cheap morrisons red wash liquid as had no blue, worked a treat my only mistake was adding it all at once , by the time i got to the last of my mould items the silicon had started to set so it wouldn't work, def my error, next time i will only use half at a time, , i used a plastic bowl, cold water and a good squeeze of wash liquid, thank you for the great tip, will have lots of bespoke buttons now :)

audreyobscura (author)  mysterymayhem4 months ago

bespoke all the things! Post pictures of your castings?

TheVClique5 months ago

This sounds great! Do you think I can use DAP Clear 100% silicone sealant?

I tried this yesterday around 8pm, and the mold is still squishy! I was wondering why this may have happened. It's been sitting for about 17 hours and it's still just as squishy as it has been. Did I not use enough soap? Did I not knead the silicone enough? Please help. Thank you! =)

lakisok6 months ago

I am trying to recreate a hand mold made in my patio concrete from my children's hands and our then dog's paw prints. The impression is in the pressed and colored material. We are moving to a new house and I want to preserve their prints for posterity. I think I may need 2 ft square more or less how would I apply it? and my idea is to then pour plaster of paris (spelling) over mold to recreate the original impression.... then air brush paint a patina. so Qs are:

1. how much silicone is needed? And how do I apply

2. what do you suggest I use and by what method should I apply the plaster

I would try a product like an air dry clay to reproduce your hand and paw prints. You can pat the material over the images you want to keep, peel it off carefully & let it dry thoroughly. Then you can either use more air dry clay and make the positive impression with it or go through the whole mold making, plaster casting routine to make your memento. Or buy a kit at one of the craft stores to make your mold. I used air dry clay to preserve some family signatures that were put into the wet cement of the house my husband's grandfather built. The house had to be sold and his sister wanted the signatures preserved. I never got around to making the reverse impression from the air dried clay.

I've seen this method somewhere but with a different appliance technique. Though I can find anywhere if this type of Silicone mold will be good to try and make smooth clear plastic casts, do you know if it will? I saw some youtube video trying to say Platinum cured silicon is pretty much the only one for that...

audreyobscura (author)  CiprianoHernan5 months ago

That would definitely be the case - this method is a bit rough, but still great for quick and dirty casting.

Thanks for the reply! It's been a while since I actually had someone answer me when I ask about things like this. Anyway, I was hoping this method could atleast even be capable of smooth surfaces due to the smooth-on molding material are far too expensive just to try and mold small parts.

I guess I'll have to deal with it though if I want my result to come out any kinda of professional quality. Thank you for your time!

SparkySolar made it!5 months ago

working on making spec soap requests

stinebusch6 months ago

This is amazing! I can't wait to try it out. I have some questions, maybe someone knows the answers?

How did you make it a complete figure? Cast the other half and then glue? Can you cover it in two halves of silicone? What's a good way to do this?

Can you cast any material, like plaster, fine sement or molten plastic in this?

Is it a good idea to use a bit of Vaseline on the casting object to make it easier to detach or is this simple anyway with silicone?


pocholox86 months ago
I am definitely getting a dinosaur just to name it Jesus, damn isn't that the smartest name! you totally changed the way I make casts thank you jesus!
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