[Central] Moldmaking for newbies

Not open for further replies.

falcon NL

Well-Known Member
Welcome to the central mold making threat. This threat is to help the beginner moldmaker on his way and to explaine the step that are needed to make a final product.

Help I don't see the answer to my question!!!
Take it easy, relax breath in and breath out.... good. For every project there are different questions, so its a possibility that your answer inst here. Just ask ( in good grammar) what you need to know. I could be that it takes a while before you get a answer so have some patience.

Whats the difference between a model, mold and jacket

Well that rather easy.

Model: is the object what you want to make a mold from. In this case its the masterchief's head in clay.
Mold: This is the flexible rubber layer that you are brush on to the model.
Jacket: This is a hard supporting jacket for the flexible rubber mold. It keeps the mold in the right place, this layer will be bush on the mold.

The beginnings of mold making

These steps are a summary of what you need to do. You still need to do some research yourself before even attempt to start.

Step 1:
Buy some oil-base clay.
There are a lot of different sorts of oil based clay.The most used clay is Chavant NPS (Non-Sulphurated Plasteline) clay.This comes in a couple of kinds .
- Chavant NPS soft (hardness 4)
- Chavant NPS medium (hardness 7)
- Chavant NPS Hard (hardness 10)

There is a alternative that is widely used. These are the Roma Plastina and the Van Aken Plastalina. For a Masterchief helmet you will needing a lot of clay, The big question is how much...well Adam?
Adam said:
A helmet will take about 25 - 30 lbs of clay to sculp.

Step 2:
Place the clay on you manique
Make sure that the thickness of the clay is about 1,5 / 2 inch all around .On the top of the manique it needs to be around 3 /4 inches. This is necessary for padding later on and for movement of the head. After this is done you may want to insert visor, this way you can build around your visor and have the some reference points. Now you are ready to build up you model to the shape you desire (masterchief helmet)

Step 3
Done with sculpting
If you are done sculpting, you are done sculpting. This sound weird but read on. If you found the time,money and inspiration for a project like this you need to be a 100% satisfied with your result. Take the time with your sculpt and work on it until you are satisfied. After you start beginning on the mold there is no place fore little adjustments.

Step 4
make preparations
Before starting on the mold, you need to have a parting seam. You can create a parting seam by making a wall of sheets of thin/metal or the use of oil base clay. The best way to hide a parting seam is to make use of the lines that there are in a object. This way it need less work after the de-molding. I recommend that you will apply some mold release before starting.

Step 5, part one
Making the mold
Now you are ready to make the mold. For the best result you cannot cut down on this part. You will be needing liquid 2 part rubber that can be thicken and brush on to the model. The 2 most commonly rubbers are,
- Polytek 74-30 with Polyfiber to thickenen it.
- BRUSH-ON serie from smooth on.
The first coat will be barely thickened, so that it can flows in to all the details, then the next coat a little thicker, and so on until you have built up the rubber to about 3/4 - 1 inch. You are only doing this at one side of the parting seam.Alway read the instruction's on the can, and use a respirator. Don't try to speed up the process by messing with the relations.

Step 5, part two
Making the jacket
The jacket is the part that keeps the mold on this place. You need to brush it on the mold and until its about 2/4 inch thick.There isn't one material that commonly used. It really up to the maker on what he want to use for the jacket. There are a couple that i recommend.
- Shell Shock (Smooth on)
- Plasti-past (Smooth on

Step 5, part three

Preparations for the second half
Remove the wall, apply some mold release on the parting seam so that the two parts don't stick together. Do steps one and two on the other side.

Step 5, part four

afterwards treatment

This mold is now complete. You should drill some holes through the parting wall that you created, so that you'll be able to bolt the two halves together. Pry the two halves of the jacket apart, peel the rubber off your model and place them into their corresponding jackets, put the two halves together, bolt them, and your ready to make your first casting.

Step 6


Polyurethane is the most used material for the actual helmet. There are people that use custom mixes (like Sean) but that to difficult if you are a beginner. The most commonly used polyurethane is Smooth-Cast 300 (Smooth On). Its a necessary that the polyurethane is a rotocast material.
mixing accordingly

step 7


Using a rotocasting resin (Smooth-On) you will mix a moderate amount of resin .Not enough to fill the helmet mold, just enough to coat the sides to about 1/4 inch. Pour the resin into the mold, and rotate the moldso that the resin coats all the sides as it cures. This will make a hollow casting. It's a little tricky to get it right the first time, it may take some practice, and a few batches of resin to get a uniform coating on the inside of the mold.


Please take the time to read the above.These video's are nothing more then a visual explanation

Good explanation about mold materials

Brush on Poly 74-30 with Polyfiber
This is a one part mold with a two part jacket. This isn't going to work on a Masterchief helmet because of the shape of the helmet.

Plastipast demo

Smooth on instruction video

Adam Video ODST helmet
Adam said:
Note - This isn't the BEST way to make a helmet mold. Normally you would get metal thin plates, and do a two part mold... but hey, this is how I did this one.

I want to say thank to :
- Sean for helping me with the info about rotocast, shell casting and the materials that he use.
- Adam for this site.
- The video tutorials threat
Last edited by a moderator:
Well i use the tools that are available at my local art store. Over the time that i have been doing this i have collected some tools that people even use in surgery, a good example of tools that experience (pro) people is :


I don't know what you are planning to sculpt (im guessing the MC ;)/wink.gif' class='bbc_emoticon' alt=';)' />" border="0" alt="wink.gif" />) but you will be a lot less then that. A good starting kit would look something like this:

what series of Brush On would you suggest? since there are a few to choose from and im afraid that 40 might be too soft and sag
zeronifty said:
what series of Brush On would you suggest? since there are a few to choose from and im afraid that 40 might be too soft and sag

Well I'm using brush on 35, but i dont see any reason why you can't use 40. The Shore is good and if you made a jacket, there isn't anything wrong with soft and sag. It makes it easer to pull the mold out of the jacket, and form the model.
Last edited by a moderator:
I'm nor familiar with task 8, or for that matter know the product. I do recommend Smooth Cast 300 serie, because these are good products, easy to use, and easy to sand.
Hey i was wondering How much silicon do you really need for One Mold? could i get like to 2 of the smaller size or do you need 1 Gallon?
I have been looking in the fourms ang i cant find out where to get the mannequin head at , dose anyone know where i can get one at?
Well one gallon is most of the time cheaper then two 1/2 gallons.

Thank you for your input and for looking out for people with little cash. You should repost it in the "Where do I get" threat.

@chalupa lover,
I found it myself though Mike's link. Be sure you check the size of the mannequin head. If you don't want to buy online, you just look in some hobby shops.
Well I have a question. AND yes I have read the whole thing. I have started my helmet and I'm about detail the clay but I don't have time to put a visor in the clay and so my question is What can I use instead of an actual visor or do I even need anything there?
Well you do need something to support the upper helmet.You can use a piece of plastic that you can bend in a ''visor'' way, you can also you clay to fill up the space( but then you will be more clay, and therefore more money spending).

I would strongly advice to use a visor, you are going to need one any way to make you helmet complete. Why wouldn't you spend those 2 hours for implanting a visor? You cast would look better and you will have better reference points...

Other then a sheet of plastic or clay i can really say if there is another option.
request for "tutorial" video:

Can we adam or sean or someone to make a quick 30 second video or whatnot of them kicking around a casted helmet. I'd like to see more about the physical properties of smooth-cast.
A video is being uploaded now if you really must know... sean does not smoothcast, its another type of material... but the one in the video is a smooth-on plastic helmet

Last edited by a moderator:
Let's say I have a finished pepakura-based hand plate. To make a mold, I'm thinking that if I just made a small container out of cardboard, I could just put the hand plate in, right side up, and pour silicon molding material over it. The problem is, I don't think that the bottom/inside half of the plate would be even with the other side (if you put it on a flat surface the top wouldn't be level).

So I pretty much don't know how to do it. How could I make a mold of a hand plate?

And to mold a hand plate, do I need to use fiberglass or could I just resin it with a few extra coats inside? From what I've read, fiberglass is a pain to work with. What about using a casting resin such as AeroMarine(<-link) instead of fiberglass?
Hi, I am currently building a pep based ODST helmet and I would like to cast it afterwards.

I have read through this thread and watched the vids but I am still a little confused.


-What is the best silcone to use; Rebound 25 or Mold Max stroke (or other)?

-Thi-Vex thickener is neccessary for helmets, right? (only for certain areas)

-What is best to use for the jacket? I have seen the Plati-Paste but I would rather build a jacket that bolts together.

-What do I do around the bottom lip of the helmet? Here is what I was thinking; Add extra material around the lip of the helmet (to make the hole smaller); while siliconing, overflow onto the new material. Make a cast using the mold and cut off what remains of the material that was added. This is all to make sure the entire lip around the base of the helmet gets cast.

-Why are two part molds better? (the ones using the metal stips); I would think one part molds with one seam would be better (for fewer seam lines.)

-How much silicone, SmoothCast, thickener, and jacket material (whatever it is) should I buy?

-How much do the molds shrink? I see that SmoothOn has some special shrink free molds whick leads me to beleive that regular ones shrink.

Thanks. If you prefer to answer by PM that would be fine.
Not open for further replies.