Hello everyone, and welcome to my first Instructable! It starts with a small story attached, and then gets into the details. If you want to get to the making, just skip ahead to the next step.
Two of my close friends were getting married, and I needed to come up with a good gift. I remembered that the bride really likes elephants, and how cool would it be to make a chocolate elephant!? But what about the groom? After thinking about it for a bit, I decided he'd appreciate an homage to World of Tanks. There was an especially awesome bit of pwnage he did with a German PzII, so I decided it had to be that.
Meanwhile, I had been working on a 3D printer that was not being very cooperative. Every time I would tell it to make me an elephant, it would just stare at me stupidly. The lights were on but no one was home. As the days ticked by, I realized that I wouldn't have time to get my printer working in time to be of any use, so I would have to use alternate methods to make the masters for my chocolate molds.
P.S. This Instructable submitted by the Rabbit-Hole Maker Space as part of the Instructables Sponsorship Program.
Step 1: Bill of Materials
Oomoo liquid silicone stuff
Skulpy modeling clay (or other polymer clays)
Mostly solid model tank (nothing with toxic paints/glues)
wax (optional, but useful)
hot glue gun (with glue, obviously)
cutting tools, modeling tools, miscellaneous
plastic cups & rubber gloves, disposable sticks for mixing
mold release / corn starch
Step 2: Designing the Master Molds
Great aha moment when I realized most tanks, even lesser known ones like the PzII, can be found in kit form. $5 on amazon saved me from having to fix up the 3D printer, design a model in sketchup / blender , print it, and vapor deposition it (so the surface is smooth). The only thing I had to do was search for snap-together models (so no glues were involved), and get one in the appropriate scale. When I ordered it I worried it was on the small side, but it actually turned out to be perfect.
The elephant was tougher, because I never allowed myself the luxury of buying toys. The main worry was that the toys, designed to be injection molded in plastic or rubber, would be far too delicate to last as a chocolate sculpture. As such, I would have to make it myself to optimize pouring in a two-part mold. This presented its own challenges, since an elephant (with tusks, ears, trunk, etc.) is a very complicated shape to cast.
Step 3: Sculpting the Elephant Master
Skulpy is an ideal material to work with if you don't have a giant brick kiln sitting in your basement. It's easy to work with, relatively cheap (though not as cheap as clay), non-toxic, etc.
There are no special tricks I used in making the elephant; I just kept making it until it started to look right. There are probably much better instructables detailing skulpy techniques than I could cover in this build.
Oh wait, there are.
The only tools I used were a wooden skewer, a drinking straw, and a peanut butter knife. Don't overthink it! The reason the ears are so wide is because I wanted them to stick out (rather than lay flat) but have enough strength to survive the demolding process after being cast in fragile chocolate.
Finally, bake the clay sculpture in the oven at 250 for 15 min per 1/4" of thickness. In this case, about 1.5 hrs (to be on the safe side). If any part breaks, super glue is your friend.
Step 4: Building the Panzer Meister
After the models are complete, you want to optimize them for casting. If there are any parts that are very thin, or have very deep holes, it's probably best to fill those in or reinforce them with additional material.
Wax works great for this. It is easy to work with, will not melt plastic, it is cheap, reusable, and non-toxic. You can find it in the grocery store in the canning section. To use, I lit a candle (also a good source of wax) and held a bar briefly near the flame, then dripped it onto the model. While still warm, I rubbed it into the cracks and crevices, and used it to fill the spaces between the tank treads. Finally, I made sure that no details were obscured on the rest of the model, since wax has a tendency to pile up where you least expect it. It is also translucent, making it tough to spot. The last thing I want is a lumpy tank!
Step 5: Building the Mold Boxes
Almost ready to cast! For the tanks, I used a pop can and a sour cream container (both washed out, of course). I used melted wax to level the bottoms, since the containers were not flat. This helps make a higher-quality mold as well as avoids wasting (expensive) silicone.
The elephant was (again) more difficult. Firstly, it would be a two-part mold, making it necessary to cast twice (letting it sit for 6 hours in between). Secondly, it was an odd shape and with odd dimensions, requiring a custom container. But that's what Home Depot is for!
Linoleum tiles made a seemingly complicated process easy. For only $0.66, one tile was more than enough. To cut, just score with a utility knife, and snap. Make sure your pieces fit, then tape and glue them together. Finally, seal the gaps in the mold with a small bit of skulpy, smoothed into the cracks.
Step 6: Mixing and Pouring the Silicone
Glue or otherwise attach the masters into their boxes (so they don't move during pouring), then use whatever mold release you're going to use. In my case, I used corn starch on the elephant (based on forum advice) and nothing on the tanks. This will depend on what type of silicone you're using, but many do not need anything.
Mix the silicone according to the instructions on the box / website. If you're really lost, use videos to guide you. In this case, I bought a type that can use equal amounts, so no complicated measuring was necessary. I simply filled two smallish cups with equal parts, then poured them into a bigger cup and stirred. Keep in mind, you have a certain amount of time before the silicone will solidify (in this case, a half hour) so guess ahead of time how much time it will take to mix and pour. I was actually riding the line on this one, so anything larger than this pour might take more than a half hour.
Pour into the mold in a corner, away from the piece. Do not pour it over the piece, but let it flow around the piece. If you can, lift up the container so the stream is pouring in just a thin strand. All of this should prevent bubbles from forming on the piece itself. It's not foolproof, but it's the best way to ensure a good final product.
With the tanks, I simply poured until they were completely covered. With the elephant, I poured until it hit a point about halfway, exactly when the silicone was underneath and around the tusks but not on top. At this point I stopped, and let them sit.
Step 7: Pouring the Elephant Mold Part II
Word of advice: DO NOT USE OLIVE OIL AS A MOLD RELEASE AGENT! It doesn't do a thing.
So I spread my (ahem) mold release agent on the elephant and especially on the dried silicone of the first half. I then prepared more tanks for pouring as well as some spare parts, to use the leftover silicone from pouring the elephant.
After that, simply repeat the process in step 7 to finish the pour.
Step 8: Removing the Masters From the Silicone
This part is just what it sounds like. Start by taking apart the mold box so that you can get to the rubber inside. If your two parts of the two part mold have become one, don't panic! That's what knives are for!
Take an X-acto knife and cut along the line of where the separation should be. There's no perfect way to do this, it's cut and guess. Luckily, mine turned out ok. Trim off any excess pieces, especially if they're blocking any air holes or pour holes for the chocolate pouring.
Wash them out thoroughly, to remove any kind of chemicals or funky stuff. Food is going in here! Then let them dry thoroughly before pouring, since any water might mess up the pour.
Step 9: Making Chocolate Tanks
Here comes the fun part!
Unfortunately I did not take any pictures of the chocolateering process itself, so my words will have to suffice. We were running close to the clock, and I had to work without my photographer.
The tanks were relatively easy, since they were single-piece molds. I used 3 different sources of chocolate; hersheys milk chocolate bars, ghirardelli dark chocolate chips (60% chocolate chips), and ghirardelli white chocolate chips. The milk and dark chocolate act essentially the same, but the dark was much more liquid after melting and much more solid after cooling, so (in my opinion) it made better chocolates. The white chocolate never fully melted, no matter how much I nuked it; it just became a putty-like or frosting consistency. As such, it was completely unsuitable for making white elephants, no matter how much I tried. :(
For making solid chocolates, the process couldn't be simpler. Melt the chocolate slowly until it's liquid, stirring as you go to avoid burning. Pour into the mold, and cool in the refrigerator/freezer until it's solid. Carefully pull out of the mold, and you're done!
For making filled chocolates, it's a little more involved. This process works best with dark chocolate, adequate with the milk choc, and not at all with white. Put the molds in the freezer beforehand, to ensure that they're very cold. Melt the chocolate fully, and pour into the cold mold until it covers all internal surfaces. Pour it all back out of the mold, leaving a thin shell that solidified on the internal surfaces. The thicker the shell, the less likely it is to break while demolding, but also the less volume it'll have for fillings, so use your judgement. Put back in the freezer to allow the shell to solidify fully.
Prep your filling material. In my case, it was either peanut butter or nutella, so I basically just melted it. Use a spoon/spatula to drip or scrape the filling into the chocolates, allow just enough space for a final coating. Lastly, pour molten chocolate into the mold to fill up the end and cap off the filling. Place in the fridge/freezer until solid, demold, and you're done!
Step 10: Casting Chocolate Elephants
I made this a separate step because it's slightly more complicated.
Ensure the two halves of the mold are rubber-banded together, so that the mold doesn't move during casting. Ensure the pour holes (legs) are big enough to pour into; if not, use a spatula to fuss the chocolate into the holes.
Keep pouring until the chocolate starts to bubble out of the other pour/air holes, as this will be your only indicator that the mold is filled with chocolate.
Place the filled mold into the freezer until solid, then remove the rubber bands and carefully begin pulling the mold off. If all goes well, you will have a tasty little treat that is all in one piece. If a part does break off, you can reatttach the severed limbs with some heat. Give the poor elephant some morphine, then use a lighter to quickly (half a second) heat up the limb or stump and reattach. Carefully set it back in the freezer until the joint is solid.
To make filled elephants is difficult but possible. The trick is to cast it in two separate halves. Place the mold in the freezer, and create a chocolate shell just like with the tanks. Fill all weak spots fully, a thin shell will not be enough! Fill elephant with filling, ensuring the filling does not get in the way of the pour channels. Rubber band the two halves of the mold together, then pour in the chocolate until completely filled. Place in freezer until solid, carefully demold, and perform any repairs necessary. There you go, a brand new mostly-intact Nutellaphant!
Step 11: Lessons Learned
This project didn't go as smoothly as I had hoped, but it was a learning process. None of you are likely to cast exactly the same objects, but these tips should apply to nearly anything.
*During design, always keep in mind the direction the piece is traveling when it's coming out of the mold. If the direction is down the legs to the feet, the feet better be smaller than the legs, or your piece will often break. There is a slight amount of stretch in the silicone, so it's much more forgiving than plaster, but the stretchiness is low if the silicone is thick in that spot.
*Also during design, ensure that the holes are big enough to pour chocolate into. A pencil eraser-sized hole is too small, but dime-sized hole is more than adequate. Somewhere between those 2 sizes is the minimum size hole you can efficiently pour into.
*Though not tested, a large syringe filled with melted chocolate could potentially be used to inject it into an otherwise too-small pour hole.
*Olive oil IS NOT A PROPER RELEASE AGENT!! It will not work for this silicone. Release agents are not necessary for most things, but in vital spots, such as the seam in a two-part mold, just bite the bullet and buy a proper mold release agent.
*If a piece breaks, don't panic, there's always a way to fix it. Superglue is great for a master, since it does not change the shape of the piece like hot glue might. Chocolate can be welded back together with a quick pass of a lighter. Skulpy can be rebaked (slowly) without much risk of cracking it. My only skulpy trick is to leave it in the oven after turning off the heat so it cools down slowly.
*Chocolate should not be handled bare-handed since it easily leaves prints. Wear rubber gloves if you have some.
*Other instructables and youtube videos might handle some aspects of this project in greater detail. Use your online resources whenever possible.
*When making an instructable, try to get some pics of the finished product. :P
Any other good tips, suggestions, or project ideas should be left in the comments section. Good luck with your own projects!