Mold Making With Jello




About: Engineer making renewable energy products for African entrepreneurs.

Have you ever wanted to make a mold and cast something -- but were discouraged by the cost of casting supplies? Have you ever just wanted to make one duplicate -- rather and one thousand? Perhaps you only wanted to make one or two chocolate book marks or plaster casts of an ink jet cartridge...

Well, here's a very DIY, cheap an recyclable method to make molds for relatively low temperature casting.

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: Materials

You will absolutely need:

Gelatin -- I'm using Jello
A vessel to pour in that will hold your positive item
Mixing container
Mixing Stick
A refrigerator with space for your vessel

You may need:
Skewers or other support device
Hot Glue

You probably want:
Chap Stick or Vaseline (chap stick being "edible")

Step 2: How Much "Stuff" Do I Need?

This is very easy to determine.... But first, here's some rules for the positive.

1. No undercuts - that is, if the mold material goes over (or into) your positive - you won't be able to get it out (without some surgical maneuvers).
2. Avoid super fine detailing - I haven't experimented with this yet, but it seems like it would be bad.
3. Don't let the positive rest on the "floor" **

So how much gelatin do we need? Lets do a "dry" run.

First, place your positive into your vessel. Now, fill with water (you may need to hold your positive under). Next, remove the positive and measure how much water is left in the container (you'll probably be pouring off into a measuring cup).

You will need one 8oz serving package of Jello/gelatin for every 3/4 cups of water. I have not tried higher concentration (yet), but feel free to experiment as a less "jiggly" mold would be better.

** There is an exception to this rule. That is, if your positive has a flat side that doesn't matter (like the back side of a chocolate bar) - it is beneficial for that back side to rest on the "floor" of your vessel. This was the case for the Tetris Ice Cube Tray.

Step 3: Positive Preparation

Jello is very sticky as it sets - but things don't like sticking to it once set. So, you'll probably want a mold release to prevent the Jello from grabbing onto your positive. As I am going for "food grade" I'm using Chicken Poop.

Now, chicken poop does not come from the backside of any fowl. It's actually a brand similar to chap stick that uses soybean oil among other things. Technically, it's edible "lip junk." So smear it over your positive and rub it in.

Now it's time to place in your vessel. If your positive is to rest on the floor AND it floats -- you're probably going to want to use a dab of hot glue or other adhesive to keep it down. If not, you can build a stand with wood skewers or make a little suspension structure as not to interfere with the mold.

Hot glue being my temporary adhesive of choice, I fired up the manual hot glue applicator and secured my positive (an apple) in place.

Step 4: Mixing and the Pour

It beings with hot water. As we're doing a rather high concentration of gelatin, really hot water is good. You don't necessarily need to boil the water - but it's not a bad idea. Slowly mix in your gelatin powder and continue mixing/agitating for at least two minutes (after all the powder has been added) to ensure everything has fully dissolved.

Once fully mixed and your positive ready -- pour your mold material into your vessel. Then move into your refrigerator and allow it to cool/set.

Step 5: Demolding

As we're using gelatin, you need to be careful de-molding. Slowly separate the positive - poke it with a sharp if necessary to start the separation. If all goes well, it should pull right out with minimal problems.

Should your mold tear beyond recognition -- see the last step.

Something I have not tried yet... Gelatin will freeze (at a cost). So if you're having a lot of problems, you could theoretically freeze everything -- then try again. Removing your positive from a solid structure is much easier.

The cost: Gelatin looses a significant amount of structure when thawed. It maintains shape (for the most part), but looses a lot of structural integrity (as much as gelatin could ever have). My advice for those that freeze their molds -- pour your cast in the frozen mold. This is a better alternative over Ice as it seems that gelatin does not expand as much as water does when frozen (strange, I know) - this makes removing the positive much easier.

Step 6: Casting and Thing That Go Wrong

Before your pour your cast - you may want to add a mold release (like chap stick et. al.). Unless you only plan on making 1 part. If that's the case, see the next and final step.

I'm pouring chocolate as it seems to be the only non melting cast material I can find around Instructables HQ. Plus, chocolate is tasty :) Going too hot is dangerous given the low melting point of gelatin - so be aware and experiment first ;) I allowed my chocolate to cool off a lot before pouring - probably overkill, but better safe than waste a half day's worth of work.

Things that go wrong -- Don't do these things....

1. Don't use olive oil as a release agent when making your mold -- the oil will float and you won't get a good separation. But, by melting and setting -- you can remove the excess oil.

2. Pouring gelatin into your gelatin mold probably won't work -- other than for non separable decoration.

3. I personally wouldn't eat my mold material...Mostly because of the high concentration of gelatin. It's also labeled "Not people food" in the Instructables HQ fridge -- so no one gets the idea it's up for grabs :)

Step 7: The Last Step -- Recycle

Personally, I wouldn't eat the gelatin... But, gelatin has an amazing property - heat it, and it melts. Re chill it and it resets :) You don't get that feature when working with commercial mold making supplies.

This has awesome implications - you can re-use your mold making supply over and over again. Gelatin does have a finite cycle life, but I have yet to hit it (it seems rather high). Just throw it in the microwave on medium power and stir once a minute until completely liquid again - be sure to check for small bits that need a little more time to melt down.

So, if your mold tore apart when you tried to release (at any point).... Melt it down and try again -- perhaps with a little more gelatin powder? Then give it another shot.

What about contaminants?
Oil based mold releases float on top of the gelatin, so when your melt down and refrigerate -- you should have a film of release agent on the top of your solid gelatin -- you can simply wipe it out with a paper towel.

Happy mold making :)

Let me know what you make -- I'm considering casting a plastic soldier or hood ornament just to see how well the gelatin takes to it -- and how the details show up :p

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

    54 Discussions


    11 years ago on Introduction

    Crisco makes REALLY GOOD mold release. Just smear that stuff on. I made a bunch of white chocolate oranges this morning.

    1 reply

    12 years ago on Introduction

    I just came across a couple of books with interesting information on making gelatin molds and agar moulage molds. Turns out gelatin is better than I thought, and used to be common for low-volume casting (up to a few dozen things, I think.) Very interestingly, it IS reusable---you can melt it down and use it to make another mold 5 to 15 times. Cool. (It's not as reusable as agar moulage, which you can use 50 to 100 times.) To make a gelatin mold more durable, you can swab the surface with a solution of alum and water. That will make it tougher and more heat resistant. (1/4 pound powdered alum to 1 pint hot water). You can then apply a mold release that's just stearic acid in kerosene. (melt 1/4 pound stearic acid and mix it with 1 pint kerosene.) To make the molds last a lot longer, you can use mostly glycerin or propylene glycol rather than water when cooking up the gelatin. It will dry much, much more slowly and you can get a bunch of casts out of it over several days. For details, check out "How to Make Professional Molds and Castings, from Plaster to Plastics" by Ralph Travers. (If your library doesn't have it, they can get it by interlibrary loan; that's what I did.) For agar moulage recipes and instructions, check out "The Materials and Methods of Sculpture by Jack C. Rich. I did some research, and the best place to get agar agar powder is usually from a local asian grocery store. Most of them sell "Telephone" brand agar agar in .85 oz. packets, and it's good stuff. The big advantage of agar agar is for lifecasting. It has a low melting point and an even lower re-solidifying point. (It has "hysteresis," meaning it doesn't like to change state, so you can let it cool well below its melting point before it will go ahead and re-solidify. For life casting, that means you can let it cool almost to body temperature before putting it on somebody. For non-lifecasting, gelatin is likely better. I think it's tougher, and easier to apply, and its higher melting point means that you can cast things in it that get pretty warm when they set. (But not really hot.)

    1 reply

    Reply 5 years ago on Introduction

    Hi! I would love to try out the agar agar moulage method with my sculpture students at the local art school. Sadly the libraries in Latvia dont have the books you mentioned and amazon doesnt post to here either. Would you be so kind and please tell me the recipe I could use? I was thinking of casting their faces with this method+ plaster bandages.

    Best wishes,



    6 years ago on Step 7

    Nice, Gelatin who would of thought of it for other things besides silly fun. I have heard a similar and purchased a casting that is recyclable from a company called Composi Mold.
    Still yet to microwave my food safe mold material. It's very hard to the touch and smells sweet like candy. Appreciate the insight. Is there a way to use the non-flavored gelatin in the same manner?


    7 years ago on Introduction

    I have witnessed some great jello casting before when I was a culinary intern out of school. I have tried unsuccessfully to find some of those chefs who worked worked out the kinks (facebook. . .)

    They used Knox gelatin (unflavored) and made a super tight mixture - enough to fill a 5-gallon pickle type bucket.

    They would invert & weight busts of presidents, plaster easter bunnies / bunny heads / animals etc. with an under tray to catch the spill-over.

    After the bucket had hardened in the walk-in cooler, a quick dip in hot water (steam kettle) and the entire mold comes out of the bucket.

    Careful cutting around the item and laying out the cut gelatin like flower petals on a table made reassembly easy.

    The cut outs were re-assembled either in the bucket or with duct-tape.

    They then poured in a mixture of chocolate & wax.

    After flattening the seams, you had an identical replica in shelf stable chocolate.


    8 years ago on Introduction

    Have you ever tried doing this with agar-agar instead of gelatin? (Agar's kind of the veggie substitute for gelatine, but it melts at 85 degrees C and solidifies between 32-40 degrees C, which could be more convenient than gelatin). I'm trying to work out whether this might be suitable for life-casting a hand?


    Reply 8 years ago on Introduction

    Unfortunately, no. I tried this a few times with super concentrated batches of gelatin. I placed the gelatin container inside a bucket filled with icy water - and then left my hand inside for 1.5 hours. Hands are just too hot - the gelatin doesn't set around your hand :/

    this works wonderfully on fairly small or light objects. unfortunately, this time, i needed to make a cast for heavy stuff. after several disasters trying various ways to cast my husband's tools (hammer, wrenches, screwdriver)--they are a little heavy for most suggestions,( and he'd get ticked if they had jello, silicone, etc on them,) my daughter &i had an epiphany. salt dough. 2pts flour, 1 pt. salt, 1 pt. water. kneaded it until it felt like clay. we used 1/2 the salt dough on the bottom of a lg. cookie sheet, put cheap plastic wrap on it, lightly pressed in his hammer, wrenches, & srcewdriver, put more plastic wrap on top, and the other 1/2 of the salt dough on top of that, pressed it down pretty firmly, and froze it for about an hour. after we removed the tools (by tugging the plastic wrap) we had 2 half molds. the chocolate also set up very quickly. so, the hubby gets life size peanut butter cup tools on father's day.


    10 years ago on Introduction

    To be honest I only clicked this instructable because I thought the picture was the brain bug from Starship none the less.

    This is for larger scale molds, but it's really cheap. You take a bucket of soapy water, the soap keeps the silicon from sticking to you, and then you squeeze an entire tube of "GE silicon sealant" into it (apparently you have to use the stuff that stinks, it won't work with the unscented kind), you then pat at it gently till it sort of balls up in your hands, if you press hard it will stick to you and it's a bear to remove, but you can handle it very gently till it starts to cure and then you will be able to remove it from the soapy water as a ball and mold it around whatever you were planning to make a casting of. In 12 hours you can cut it from your item and viola! You now have a clear silicon mold that will last for 5 years and that cost under $10 to do. Apparently it's really good at showing details as well.


    10 years ago on Introduction

    HELP! I really want to cast my hands/arms in plaster for an art project but I can't figure out anything that might work...the jello molds seem close enough but I don't know how I could get my hands out after the jello set without damaging the arm part of my mold. Also, I don't want to have to order any weird mold-making stuff.....i live in a tiny town so jello is about the only thing i could come by... some advice please??

    5 replies

    Reply 10 years ago on Introduction

    mold each hand in a long thin container like a juice pitcher. When it is set, pull the whole jello thingy out of the juice container and carefully cut it in half. Then carefully put the two pieces back in the juice container. And voila, you'll have your arm/hand mold. You'll obviously need an assistant for this.


    Reply 10 years ago on Introduction

    Can you post pictures of how your mold came out? I've tried this - using half gallon milk jugs (the tall type) and then that jug was placed in a 5 gallon bucket of iced water to set the jello.... The jello started to set everywhere except around my skin as my body heat didn't allow it to get cool enough.


    Reply 10 years ago on Introduction

    yeah that's what I've found as well. luckily I've managed to find a different mold-making material :D


    Reply 10 years ago on Introduction

    Jello isn't the way to go for life casting - your body heat keeps it from setting....

    Personally, I'd use alginate. It's a fairly common life casting mold-making item which should satisfy your "no weird mold-making stuff" requirement.

    Douglass and Sturgess has it - it's called Dermagel (the same stuff used by dentists to make molds of your teeth):$RETRIEVE?sortcode=BC030728&html=display

    You can also use Moulage - which is basically like Jello and reusable ;)$RETRIEVE?sortcode=BC030733&html=display

    No worried about living in a small or even tiny town... You have internet access, so you're not so remote that mail can't get to you ;)


    Reply 10 years ago on Introduction

    I actually ended up just dipping my hands into melted (but not insanely hot) wax and then filling the wax molds with plaster, which worked really well! alginate does sound like fun soon as I get more money (haha...not anytime soon) It would be fun to try out. :D thanks!