Making figurines for use in tabletop gaming is a passion of mine. I went so far as to start a tinsmithing company that pewter spincast metal figures. Today, you can 3d print very nice looking resin or plastic figurines, but can you convert these to metal? Some people have a love of metal figurines. They are tougher and have some heft. For many decades, this was the only way to get figurines, and many are nostalgic for this medium.
There are two ways to convert 3d printed models to pewter metal copies. You can create a room-temperature vulcanizing mold, and hand-pour molten metal into the mold to get a copy, or you can create a heat and pressure vulcanized spincast rubber mold and use a spincaster to take molten metal and create pewter copies.
There are intricacies to both methods, and the quality of the copies and the number of potential copies is drastically different. Room-temperature vulcanizing molds are good for low volume, home use. Spincasting heat and pressure vulcanized rubber molds require specialized equipment and are not suited to home use.
RTV Rubber Molds For Metal Casting
Smooth-On, Inc. makes some fantastic rubber to create molds for copying models in metal. They refer to their casting as tin casting, but it would work for any lead, lead-tin or tin mix. The low temperature melting point of these metals means that they don’t have to be so hot as to damage the mold’s rubber. Here’s a link to Smooth-On’s page on RTV (or room temperature vulcanization) rubber for tin casting: https://www.smooth-on.com/category/tin-silicone/. Have a look at this YouTube video to get an idea on how to make a mold:
Once you have a mold made, you can heat metal on a stove, then pour it into the mold (carefully!) and let it cool. Once it has cooled (less than a minute), you can open the mold and extract your metal copy. You may need to scrape and file the metal to get rid of the seam line that inevitably forms from the metal pushing into the gap formed by the two mold halves. The nice part is, once the mold is sufficiently cooled, you can pour more metal in and get another copy. Rinse and repeat!
Molds only tend to last for anywhere between 25 and 100 copies made. The rubber will eventually tear and degrade over time, but that’s quite a few copies. Many a wargame army has been made in this way. And if you have the original model (which isn’t damaged in the making of the mold), you can make another mold and get another 25 to 100 copies.
Spincast Rubber Molds for Metal Casting
In my past life, I was a master mold maker and owner for a metal miniatures company that made figures for wargames and wargamers. The original models were made by very talented sculptors working in the medium of greenstuff, a blue/yellow epoxy putty that, when you mixed the blue and the yellow halves, will begin to harden. You can add bits of greenstuff to the model as you go, building up a figure for casting. The reason that this material was so good was that it retained some flexibility under pressure, and it could withstand the temperatures necessary to make the heat and pressure vulcanized rubber molds.
The advantage of spincasting is that you can generate a large amount of figures in a short amount of time. I was able to make between two and four molds per day, each with around 15 figures in the mold. Once vulcanized and the pour gates and air vents cut (by hand), the mold could be used to cast figures. You could take those four molds and cast them that day ten times, giving you ten of each figure, up to 60 unique figures. So you could make 600 figures in a long day of making molds and models. I could make another 600 figures the next day, too! This is how small manufacturers make stock of models for sale.
Those molds will last virtually forever. I have been making molds for 20 years now, and I’ve never burned out a mold. They’re the same material as a truck tire, so they’re tough!
Today, you can print a 3d model with a DLP resin printer at quite high resolution, and use that model as the original (or master) model for a mold. In spincasting, you can put somewhere around 15 figures in a mold, depending on their pose. A person standing tall and straight with their hands by their sides is far thinner than a huge barbarian with his arms outstretched, so you can put more skinny guys in a mold than barbarians!
The master models will be subjected to high pressure (around 2000psi) and roughly 310°F or 155°C in temperature. So, to withstand this, you’ll need to use a special printing resin that is good for high temperature resistance. Take a look at IFUN 3D Printer Resin Clear 405nm HiClear HiTemp. Here’s a link: https://amzn.to/3gDXsEy
Models made with it have high hardness (good for withstanding the pressure of vulcanization), and can withstand 356°F or 180°C, more than is necessary for rubber vulcanization. It has some problems with loss of detail on the support side of the model. For a figure, support should be on undersides of items to not obscure critical detail. It’s not too bad for tanks and other vehicle models, though, as you can support the bottom of the vehicle and sand/file this flat.
Take a look at this video for an idea of how to make a spincast mold for casting:
Figurine Design For Casting – How To Make Models That Will Easily Cast
To metal cast a figure, you’re either pouring molten metal into a mold and allowing gravity to push that metal into the cavity, or you’re using centripetal force from spinning to force the metal into the mold cavity. In either case, you’ll have to design your figures (or choose your figures if you’re getting them from places like Thingiverse.Com) with certain characteristics.
Metal doesn’t like to go opposite to the direction that it’s being poured or forced. So if you place the figure upside down, and pour metal into the base, you shouldn’t have the figure holding a sword pointing down that isn’t attached to the base. The metal will go in the feet, and you’re asking it to go up the leg, into the torso, then the arm, and then go against gravity and fill the sword. That’s difficult for metal to do, as it’s cooling the whole time it’s away from the heat source. So the metal you pour could be 50 degrees cooler than when you scooped it from the metal heating in a pot, only two seconds ago!
This is why you see some strange poses on metal figures from time to time. It’s easier to cast if you don’t ask the metal to go against the direction of pour. To create that figure with the sword pointing down, you can print the arm, hand and sword separately, and then glue the torso and arm pieces together later. This, however, makes the model more fragile, as you’re relying on the superglue (the best glue for attaching pewter or tin to anything else, like more pewter or a plastic base) to hold.
Simply 3d Print What You Need!
The obvious counter to this is to just print more figures on your 3d printer. I can print around eight 30mm figures on my AnyCubic Photon at a time. I start the print before I go to bed and the figures are done long before I get up in the morning. I can start another print just before I go to work and it’s done before I get home in the evening. If I do this all five days of a typical work week, I can have 80 figures printed by Saturday morning. Most games don’t need that many figures, and even if you need more, you can just print more.
The upside is that you’ve already got the 3d printer, and you can just keep printing. You can do those poses that you like with the figure without having to consider the flow of metal. You will, however, have to remove supports and clean the figure up but that’s not too bad of a job. You could probably have all 80 figures cleaned up by lunch on Saturday!
To me, that’s what I’ve decided to do. I no longer need the garage full of equipment to vulcanize molds and pour molten metal safely. I can both create great looking miniatures and I can park my car in the garage. That’s a double-win for me!
How much does it cost to 3d print a miniature?
Miniature figurines typically stand around 28mm to 35mm, and stand on a base of between 25mm and 40mm round. The resin cost, using a DLP resin printer, will be between 20¢ and 40¢ per figurine, depending on the bulk of the figurine.
What 3d printer is best for miniatures?
To get the highest quality miniature, use a DLP resin printer, like the AnyCubic Photon or Elegoo Mars printer. These DLP resin printers can print several miniatures at one time, and the quality is easily tabletop standard. Use a Z-axis height of 0.025mm (or 25 microns) when slicing to get the best quality.