There has been discussion about using Insant Mold to make duplicates and multiples of components on the forum, and I recently purchased some. After a lot of trial and error, I have been able to come up with some simple instructions which allow you to make decent copies of objects. A few opening remarks;
The copies made are not by any means perfect - they often have minor imperfections and do not reproduce detail as well as commercially-produced components or original sculpts. One may get much nicer results with resin or metal casting using silicone etc. However, those methods can be expensive - especially for a small run - and often require specialized equipment to accomplish.
Highly complex components are not well-reproduced by these methods - a full figure could not be made, for example. The best results are seem to be got from flat objects, and objects which exists mostly in a single plane (shields, swords etc.)
The minor variations in the duplicated components mean they are best used on rank-and-file models, and when partially covered by other things. I have duplicated shields, for example, which I have then put laurel wreaths on, allowing me to hide minor imperfections.
These techniques should not, of course, be used to evade copyright or perform any illegal activity. This tutorial is offered simply for informational purposes and no other.
With that out of the way, it must be said the results are rather nice and much easier than making multiples of a single item in a "factory assembly line" process in many cases. Here is the equipment you will need - all of it is readily available.
A kettle to heat water (some people maintain that a microwave can be used to heat the water; I have not tried this. I have found that the water needs to be as near boiling as possible to get excellent results, so a kettle with a theromostat switch works very well).
Milliput - I used the standard grade. Milliput works better than Green Stuff because it is softer when mixed, and more easily squishes into gaps. It is also easier to scrape excess away and can be filed and sanded more easily. You may find another putty which is good, but I had best results with Milliput.
A heat-proof dish to hold water.
A fork or other utensil to remove the Instant Mold from the water (a fork is good because it has tines which drain the water, but is not so small and sharp the Instant Mold bends under its own weight).
The Instant Mold. There are various brands of thermo-setting mold material on the market, but Instant Mold is the one I have used.
Sheets of fairly sturdy plasticard or other hard, smooth material.
Pieces to be duplicated. For the purpose of this example, I have used some pre-cast components, but one should only use this to duplicate items one has sculpted oneself.
Not shown here, but necessary, are paper towels to dry items, and superglue (for two-sided molds).
Heat the water to boiling point and pour it into the dish, putting the Instant Mold inside. It may float to the top, and I find it useful to use the fork to hold it down.
Instant Mold seems to make the best molds when you begin with a square block. If you are reusing the material (which you can do) the best thing to do is remove it from the water after a few minutes and mold it into a rough block with your fingers. The Instant Mold is quite safe to touch, but the water will be very hot, so use the fork!
When you have made the blocks, pop them back into the water to continue to soften.
There are three different kinds of molds I have discovered one can make - there is the single-sided or press mold (which is a mold of a thing which lies flat on a surface. The mold is simply filled with putty and then smoothed off). There is the double-sided mold which produces a fairly complex shape, and there is the hybrid mold which I call the "one-and-a-half" sided mold, which is made from a single-sided mold. We will discuss the single-sided mold first.
Place the item to be duplicated on a flat piece of plasticard, with the flat surface down. In the single-sided mold, the detail of the underside is not reproduced. This makes it an excellent method of making shields, icons, and other details where the rear is not important (thus, this method is not recommended for duplicating Kardashians).
Remove a block of Instant Mold from the water, and make sure it is fully softened. It should be easily maliable throughout, with no hard center. Once it is fully softened, dry it with the paper towel and squish it on the item to be duplicated.
Use smooth, even pressure. Make sure you do not have air or water pockets around the piece. You have a few moments to work this without difficulty. If it does not work, just peel it off and re-heat it and try again!
Use another piece of plasticard to flatten the top of the mold. Don't press too hard - if you do, the mold will cut through to the piece itself and cause problems. Just flatten the top. This makes it much easier to place the mold flat while filling it.
This step is not necessary - the molds will harden at normal temperature. But, I like to put them in the freezer for a few minutes to really set up. You can see it sitting on top of the cranberries.
Once the mold is hardened, you can carefully remove the plasticard and the piece - it should not stick too much. The mold is quite flexible, but be careful. You now have a very nice press-mold!
You can use the press-mold method for casting objects which don't have a perfectly flat bottom - you just have to accept that the back of the piece will be perfectly flat! For some applications, this isn't a problem (this shield, for example, would work with a smooth back without any problems) or can be overcome with some careful carving and filing afterwards.
Now let's work on a two-sided mold. Begin by making sure your Instant Mold is good and soft. You will need two pieces for a two-sided mold.
The water cools fairly quickly, so you will likely need to get fresh water, newly-boiled.
This is fairly tricky to describe perfectly. Take a piece of the Instant Mold and put it on the flat surface. Then, press the component into it. Do not press too hard. The idea is to set it in there, about half-way. The surface of the Instant Mold will deform, curving down like a matress with a heavy object on it. This is make a depression all around the model.
Notice that the piece has been put near the edge of the mold, and that it actually overhangs a little. This is deliberate. If possible, make an overhang for a two-sided mold; this allows excess putty to squish out and not make a messy cast.
Here, the freezer is all-but essential. Let the piece get really nice and cold - not only does this set the mold, but also helps with the next stage. A cold surface means the fresh Instant Mold tends to harden quickly, before it can stick to the other piece.
Take the mold and piece (still in situ) out of the freezer. Use another piece of soft Instant Mold (you will likely need fresh water) to squish over the top. Try to get the Instant Mold to flow over the edges of the first piece - this makes a "key" which helps with aligning the mold later.
As with the single-sided mold, flatten the top with some plasticard.
Into the freezer with it! Here it is seen sitting on top of some nicely frosted steins.
When the mold is set, carefully pry it apart. You can use a tool to help you here. It may be difficult, but apply gentle, even pressure and it will come apart.
Now let's cast something! Mix up a blob of putty about the right size (it is better to have too much than too little, of course) according to the instructions.
For the two-sided mold, squish putty into
both sides. Use a tool to press it in if you wish, and use water to smooth it off. Scrape away excess putty. The idea is to have an even layer of putty in each half, up to the level of "lip" of that half of the mold. When put together, they will make a full cast.
Sop up any excess water with a paper towel. It needs to be pretty dry for the next stage.
Apply a thin layer of superglue - any kind will do - to one side of the cast. Superglue will not stick to Instant Mold once it is cured, so it is quite safe.
If you are casting something long and thin, you can place a thin piece of wire between the two halves of the cast, to give some strength,
Squish together the two halves of the mold. Make sure they are lined up correctly. With the flat surfaces, you can easily press them together on the surface of a table. You do not need crazy pressure - too much pressure will deform the mold and make the cast thinner.
The single-sided / press mold is very simple indeed - just fill it with putty and smooth it out with a wet finger. You can leave it completely flat if you wish or, as I have done here, make it slightly concave if the application merits it (for example, a shield.) Obviously, no rear details are reproduced, and that is what one uses a one-and-a-half sided mold for.
The completed casts. The shield has a couple of small errors on it, caused by bubbles in the Instant Mold. But these are very minor, and could easily be trimmed away leaving a nice smooth surface. The helmet has been turned to show the worst of the casting line down the face - for a more detailed model, this might cause a problem. But, for a simple facemask like this it is not too serious and could easily be trimmed away.
Another picture of the components, this time showing the side detail of the helmet, which has come out very nice and cleanly. This casting would work well as a rank-and-file model, but probably not a character!
Here we see the single-sided mold with the original piece in place (truth in advertising; I have actually used a plain shield of the same size and shape. This works for this application because the rear of the shield is all I am interested in.) Notice how it fits in perfectly, and notice also the small notch I have cut out on the left side - this will work as a "key". I freeze this assembly to make the mold more solid and cold.
I then heat another piece of Instant Mold (I actually trimmed the helmet molds of excess Instant Mold - this works well. But, if you are reusing Instant Mold, please make sure you clean it well. Soap and a toothbrush works well, and you can also scrape off the putty with a modelling tool. The putty comes very cleanly off in large pieces, but the thin "wash" which squeezes out is harder to remove. If you stick on a big slab of Milliput, let it cure, and then peel it off it will take the rubbish with it.)
Then, squish the Instant Mold on the top of the piece and first mold. Get it into the "key" notch, but be careful to not let it wrap around completely (it will be impossible to open the mold!) Flatten the top with a piece of plasticard.
Here you can see the key notch filled, allowing easy placement of the top of the mold.
To use this one-and-a-half sided mold, fill the first side with putty and smooth it off as you would for a press mold. You will want to make a suitable depression in the putty, so when you push them together the mold halves can fit. Then, simply press the mold halves together and let it cure.
The end result is very good - the better detail is got on the side of the first mold, but the detail on the rear is acceptable. Of course, for the average shield the only thing one is interested in is the curvature of the shield, not any details, so this is a minor point.
