Make a silicone mold from common household materials in your kitchen in 1 hour

Picture of Make a silicone mold from common household materials in your kitchen in 1 hour

Taking off from this BRILLIANT 'ible I have started making silicone molds on the cheap and thought I would share. This is incredibly simple and fast and can be used for a ton of casting ideas...

Here is the podcast I did on it:

The basic instructions are below....
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Step 1: Materials

Picture of Materials

You will need:
  • SIlicone Calking (the stuff that stinks like vinegar or acetic acid) I have a calking gun but you can get smaller tubes of it at the hardware store
  • Mineral Spirits (this is just paint thinner but somewhat less toxic than the rest. NOTE: you can use white gas or camp stove fuel but be CAREFUL if you do use that. The advantage of white gas is that it will cure the mold faster and the mold will not smell like mineral spirits after)
  • Corn Starch
  • Vaseline
  • Latex gloves (or what ever kind you like)
  • mixing sticks
  • Drill
  • Bent nail
  • Something to cast or mold
  • Small box
  • Mixing cups
  • Wax paper
  • Play dough

Step 2: Prep the item to mold

Picture of Prep the item to mold
  • To prep the item for the mold cover it with Vaseline (if it is a bit goopey use a blow dryer to melt the Vaseline and smooth things out).
  • Next cut the bottom of the box out and place it on a piece of wax paper
  • Get some play dough and fill the bottom of the box with a layer thick enough to cover half the figurine (don't put the figurine in yet this is just setting up the base
  • Press the figurine into the dough and make sure to cover 1/2 of the figure
  • Vaseline the dough and the figure (if it is a bit goopey use a blow dryer to melt the Vaseline and smooth things out).
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Thanks for posting this Instruction. I made it! Not a Play-dough toy, but a mould of an essential - and
tiny - part of my wheelchair, which would have cost hundreds of pounds
to replace (because I would have had to replace the entire footrest
system, even though only one tiny bit snapped off).

I found that
the best place to get right silicone is at the cheapest stores (in the
UK that would be Pound shops or Wilko). The posher shops sell upmarket
stuff which doesn't have the vinegar smell.

When doing my initial
test, the only alcohol thinning liquid I had to hand was Nail Varnish
Remover (an essential part of my tool box because I'm constantly glueing
my fingers together whenever I use SuperGlue!).

I needed to use only a few drops of the Nail Varnish Remover, along with a teaspoonful of cornflour and a teaspoonful
of silicone caulk (the caulk I used for my initial test had been open and sitting on my shelf for
several years).

The mould dried fully within a few hours and it worked
beautifully. Now I've got the bug I'm going to try and make a mould of
my favourite Buddha statue.

I never thought of nail varnish remover (here it is nail polish remover) Given you need less volume of it and it smells better in my opinion maybe that is what I should be using. Thanks!

How much mould shrinkage happened using this thinner?

Given that the piece I was working on was no more than 12mm long, there was no perceptable shrinkage. But you've got me thinking. My Buddha statue is about 45mm high so I'll make a point of measuring the final product and record any notable difference. I think I've caught the bug! ;-)

SixFootBlue1 month ago

Are these molds oven-safe? I was planning on using them with polymer clay, and then baking the clay at around 120C while it's still in the mold. Since it's not food-grade, I'm not sure if it would release contaminants or toxins into our oven.

TwylaM2 months ago

Thank you so much for sharing, and the instructional video was exactly the type I learn with the best, creative, fun, and provides all the steps with hands on visual material! May you be blessed in Christ as this tutorial has blessed me, and beyond.


Good tutorial, thanks for sharing; Jesus Christ Bless you! :)

Thank you for blessing people according to faith, and not holding back! I am in agreement with you, I loved this tutorial, and it was also a blessing to me.

Very detailed information.


Ibadullah Safdar

ChrisO34 months ago

Thank you so much for this great instructable. I was looking for a cheap way to thin it out to create less bubbles and this is great! I made a colour test video using different mediums to colour resin for casting if anyone is interested.

rlyndallwemm5 months ago

Forty dollars worth of failure. Probably because the State of California does not sell proper Mineral Spirits. The first batch was too thick to pour. The second was better. None of it stuck to the item properly and just fell off it, distorting the pour box and pushing out the sides. Horrible expensive mess.

C Diane11 months ago

I tried using 50/50 silicone and cornstarch since I wanted a more clay-like consistency to mold over an object. The stuff never dried and had to throw the whole thing away. I used GE premium waterproof silicone for kitchen/bath/plumbing (100% silicone and regular corn starch. What did I do wrong?

ge silicone is different and will not cure the same with corn starch. you need to use regular silicone that smells like acid.
Rossana6710 months ago

I read that aquarium rtv is food save. If I use this silicone, can I make molds for cake decorations?

JestGold1 year ago
Will be trying this to cast some 5" square tiles in hydraulic cement. From what I've been reading in the comments in Mikey 77's great post, using naphtha thins the oogoo and does not give off odors once cured, as compared to using mineral spirits or paint thinner (evidently these continue to stink well after the oogoo is cured).

I think I will try thinning the silicone with the naphtha before adding the corn starch. If anyone has done this, I'd love to hear about your results. But I will try for myself.

Thanks for a great post, and video, which really helps to see what's in store for me.
I love it!!!!! Works great. Im using Naptha.
Thank you for sharing
MechanicalMashup (author) 1 year ago
I am thinking you need to add less cornstarch and add it last... This might sound odd but do you live in a humid environment? The more humid the less cornstarch as the cornstarch pulls water from the air to set off the silicone. If your in a humid area the there will be more water in the air thus set the silicone off early.

Experiment a little.
spider871 year ago
Not a single person has has the same experience? Lol
spider871 year ago
I don't understand what I'm doing wrong.. I tried 50/50 then a healthy portion of mineral spirits then I tried 4pts corn starch 8pts silicone. However, when I add the spirits, everything starts setting up right away instead of softening.. What's going on? I'm mixing with a knife not a power tool.. Could that be it?
thomas96661 year ago
Thank you so much, been looking for an easier and cheaper way to cast molds for a long time
jhante1 year ago
Very nice instructable! I work in the industry, my company makes prototypes by casting and other methods, so I was interested to see how it can be done in your kitchen!
owsamphoto1 year ago
Could I used the mold in fondant cake designs? Is it safe or food grdae
gemini17202 years ago

check out the link for food safe mold making for cake decorating mold making
dlrlt5302 years ago
Does anyone have a silicone recipe that IS safe for food and can be put in the oven, safe up to 500 degrees? Or is there such a product already out on the market? I need it in liquid form, so I can make my own mold.
binkibow2 years ago
Hi I'm in the UK & cant find 'Silicone calking' any idea what else it may be called here ?? I have been asking & retailers look at me blankly.

the silicone calking it´s the silicone in the tues using for bathrooms, fish tanks , seel window gaps, in portugal we can get it in drog stores, i think that in ingland is the same
Silcon sealant is the same, or bath seal. You can get it in any diy store
MechanicalMashup (author)  binkibow2 years ago
Did a little research and they should not be giving you blanks stares...

Maybe try asking for bathtub sealant. Sorry that's the best I can offer.
MrRetardo2 years ago
I've used Silicone Caulking to make molds before. For thicker molds, mix in some Glycerin. It helps the silicone cure in thicker layers, as silicone caulk cures by reacting with moisture in the air.. For a release agent (keeps silicone from sticking), try using a silicone-based spray such as Armor-All.
Hi, I am in need of molds for my project (it will be on instructable once I manage to finish it). I need a mold that has a minimal shrinkage. (IE 1% max). I am going to try the glycerine (I found a bottle at my local drugstore). I was wondering if I could add talc instead or starch? Anyway I think that 10:1 by weight for the silicone glycerine mix would work ok. I'll try and give you news.
MechanicalMashup (author)  svaillancourt2 years ago
Corn starch only it's hydrophilic. This is what sets the silicone off faster. Talc will not do that. Glycerin will also help set the silicone off and thin it but I have not experimented much with it. So make a couple batches and then after a week measure shrinkage.
I have failled miserably. Going to wait and buy the smooth-on kits ;)
halo994 years ago
Would this also be safe to use with food molds? (jello) would it be eatable?
MechanicalMashup (author)  halo994 years ago
NO!!! sorry this is far from safe for that.

I would imagine that if you got food grade silicone from a hardware store and only used cornstarch that it would be safe but I am not sure it would be pourable or as manageable as the video shows.

So I say again NO it is not safe for food as is but the above suggestion may make a mold that is usable. I am no expert in this though and you are on your own if you want to experiment with that...

Dont think I am being negative or being a jerk, far from that, we love our fans. I am just being concerned about your health an like our fans to be healthy and alive :) Otherwise they don't promote us nearly as well, last I checked there is no internet connection to the afterlife...
Food grade silicone, glycerine and corn starch.
oh ok thanks
See this link for food grade silicon:

I have used it many times with great results. If you look at my sugar glass 'ible you'll see my bottle mold in the pics. I have used it to make chocolate bottles, also.
neodymium2 years ago
Could I use a non-alcohol thinner like turpatinen or a low alhol content thinglike 70% rubbing alcohol? What would happen to the mix if I didn't add any at all, because it sounds like it would shring less without any thinner? Thanks.
Anyakin2 years ago
This is why I love Instructables :)
kommodore2 years ago
Dude!!!!!!! i just try this and it turned out excellent!!!!!! thanks for this great instructable!! i was wanting to make some silicone mold for a long time, and i didnt wanted to spend like 40 dollars on 1 kg of two part rubber silicone, so you save me a lot of money, i mixed silicone and corn starch on 1:1 ratio, and then add paint thinner, the mold turns out really well, alltough, next time i will use some more paint thinner so the mix gets more runny.

So thank you!!
mschell12 years ago
if you dont add the mineral spirits, does the mold still shrink?
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