Picture of Replicating body parts in plaster
This is the first part of a two-part series on making a silicone replica of a body part. However, before we can make the silicone replica, we'll have to make a plaster replica.

*** WARNING: Because of the body part chosen for casting (in this case, a woman's breast), this Instructable may contain material considered offensive or objectionable to some readers. Viewer discretion is advised. ***
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Step 1: Gather your materials

Picture of Gather your materials
To do this step you will need the following:

1) Dermagel - at least 2 pounds (or equivalent dental alginate)
2) Plaster - at least 2 pounds
3) Plastic container for placing body part inside of
4) 2 plastic mixing bowls - preferably with measuring lines (might get ruined)
5) Plastic cups for pouring materials
6) Duct tape
7) Metal whisk
8) Wooden mixing stick
9) Gram scale
10) Box cutter
11) Flathead screwdriver
12) An old towel
13) An assistant (optional, but highly recommended)

Step 2: Select a body part

Picture of Select a body part
This is the fun part.

The first thing you'll want to do is decide what to replicate. Some things are clearly more challenging than others. For instance, casting a finger is definitely easier than casting one's right breast.

However, I say go with whatever will make you or your robot happy.

Step 3: Prepare your container for casting

Picture of Prepare your container for casting
Once you have decided what you're going to cast, you have to figure out how to cast it.

If you're casting something that you are capable of sticking into a bucket (i.e. a hand, foot or elbow), then all you need to do is find a container slightly bigger than the part you are trying to cast.

If you're casting something like a boob or a belly button, then you have to find a container that will fit nicely over the entire area of the body part.

For my first cast, I tried using an old yogurt container that was cut in half (below). This container cut off part of the breast. So I tried again by cutting in half a two-gallon water container and that was more than large enough to cast the body part (not shown).
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fxguy20002 years ago
if you want to reduce the amount of alginate you use you can always use plaster bandages for backing and to reduce bubbles try not to whip the alginate before applying it on the body. oh and for the person that asked about casting the lower extremities it is very possible but time is limited!!!! you can do a man but you have to prepare a container ahead of time and have him at full attention when the alginate goes on because it can be quite cold. you are also able to buy these kits on line complete with instructions. hope this helps
I want to do a full chest with both breasts. Do you suggest making a container like this, or just apply the alginate and wrapping with plaster bandages like for a face?
I have observed the person getting the mold done. Some times just having them sit upright can work but remember that alginate is heavy and can stretch the skin of the breast. Some times it is able to work by making a container that the person can lean into or lie on top of. Fill it with alginate and position them over the container. After it activates remove the person and fill it with plaster or wax to get your finished piece. Every chest mold for women is different some you have to have sitting some have their hands above their head. Position them and put a slight pressure on each breast and see how much give there is. If you dont want a fold on the underside of the breast then having them put their hands above their head might help but remember to have someone help support their arms while you work. It is a tough job for you it is also a tough job for the model to suspend their arms in the air for that long as well. Just observe each model and try various poses each time applying pressure downwards on each breast to make sure that is the position you want them.
If you want to do a full mold of a womans chest there are several ways to do it but all of them require the alginate to be smeared on and placing bandages in a "old style I form" across the chest before applying the other plaster bandages are put on for the shell. This added support allows the bandages to form to the curve of the breast giving you more real look and not short changing the subject of their true body shape. As for the different poses you will have to practice this part before doing the cast. Have your subject raise their arms above their head and gently press down on the top of the breast. This will give you an idea of how much stretch you will have when applying the alginate. Some models you can have with their arms proped up with two chairs. If you are lucky enough to find some one that can have their arms by their side and not have any droopage then you have found a one in a million. Other than that you might have to try laying the person down on a table or floor to do the mold. With this method you will have the breasts go to the sides and might not look right. Basically you will have to try a few different poses through trial and error. Hope this helps
I have done breast molds but each one is different. Some women you could pose them with their arms in the air or out to the side, some you have to get them to lay down to get a proper mold. The alginate is heavy and will weigh on the breast giving you a distorted look to the final outcome. The first thing I do is test the area by pressing on the top part of the breast seeing how much it stretches. You don't have to press hard or use your full hand. The side of your hand pressing down like you were wiping something off. Go slowly and you will see how much give is in the area you are molding. If the models breast is very soft then I would recommend that you have her lay on her back to do the mold. Remember Vaseline is your friend. Women have hair on their chest it is very fine but it is there and can rip out the same as eyebrows!!!! Remember they have to be comfortable if you want them to ever do another mold for you? After that just do a mold the same as a face mold. If you are laying in burlap to hold the plaster bandages to the alginate then also don't forget to lay a strip between the breasts for added security. Other than that I would love to see the final outcome. Happy molding!!! :)
mayej2 years ago
Hahaha, great choice of sticker.
Nice touch.
Is she wearing boxers?
She looks more like a guy to me
How is that in ANY way way relevant to ANYTHING? Seriously, guy...
danzo3212 years ago
Didn't you say you were going to silicone-cast it?
danzo3212 years ago
It may feel heavier but not possible to get heavier. How would that happen?
danzo3212 years ago
Might as well stick your mold back in the plastic cup to keep its shape while casting it. Your plaster is way too thick, that traps air pockets.
danzo3212 years ago
To avoid air bubbles you want to work with thinner alginate, 'scrub' the breast with a gentle tool while submerged, and your plaster should be like tomato soup when you first mix it, not like toothpaste.
danzo3212 years ago
I think I'd go with faster set time/warmer goop.
danzo3212 years ago
It is normal to mix the alginate with tepid water!
Booche6 years ago
D, how would you recommend doing nipple only? Method & Materials? Thanks!
danzo321 Booche2 years ago
A shot glass and alginate to fill..
raziz3 years ago
it is wonderful.. if the tiny bumps bothers some people, it was just caused by trapped air bubbles, rubing some alginate onto the skin before you pour should help...
Shany1203 years ago
is that duct tape?
NeuroPulse4 years ago
She does not seem to have a left nipple?
seeem6 years ago
Honestly you're much better off getting someone to apply it by hand, you'd get rid of all those awful air bubbles. If you're casting a small area like a section of chest, you could even get away with trying a warmer mix to try and minimise the goosebumps.... although normal alginate goes off far quicker with heat.
it ain't always small if you know what im sayin
Helos seeem5 years ago
I wonder if using a whisk adds most of air bubbles to the alginate mix, that's the whole idea of using them in cooking. I seem to remember my orthdontist using something as simple as a tongue depressor or popsicle stick to mix it.
fragmaster44 years ago
New Bra style  :P
Azayles5 years ago
I can tell the poor girl was cold. That robot sticker isn't exactly laying flat on her areola

 those nipples look like they could slice through hardened steel like it was butter (not to be a derogatory phrase just making an educated observation)

but seriously how cold was it in there? i could not tell if it was winter outside that garage 
joe9999996 years ago
This is a wonderful idea. Do you have any advice on using this method to mold body parts found between the legs? In the case of such parts of one particular "gender", there is the added problem of maintaining "attention". In the case of another particular "gender" there is the problem of leakage of the dermagel into the body.
*Warning offensive straight forward language coming*

If your gonna mold your husband/boyfriends man part dont. its not worth the time. just buy a dildo. itll be bigger better. Plus u wont damage his weiner.
You can also use dental aglinate.  It's the same stuff the dentists uses to make a mold of the inside of your mouth, it's fast setting, made from algee so it won't damage him.  You can find fast setting so the time will be quick.
this chick is dangerously skinny, seriously like dangerously slim.
um... i do not wanna know more... but you can prob use some Santa's little helper to maybe keep up... and have a girl keep your attention... the other one... maybe use tape...
I wouldn't use tape, just mix the alginate to a thicker consistency.
that would work too.
use the ** ring ;)
dert joe9999995 years ago
In the case of one gender, attention can be met with the assitance of another gender. or try viagra which will certainly last longer than 15 mins
What proffit in persuing the artist?
Kasaron6 years ago
Is there any way to heat the dermagel, or will that make is unstable? I figure if the gel was at least warm it might be a little less uncomfortable...
you wouldn't get the pokey nips if you pour warm liquid on em. Keep it cold for perfect moulds! 
there are detailed info on the subject on
losse the sticker
Ward_Nox5 years ago
Warning: Plaster can get INSANLY hot when it begins to harden which is why the markup studios stopped using it to make casts for doing prosthetics
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