Casting Techniques - imyownyear/Z-Butt GitHub Wiki

Multi-shots

Multi-shotting is the process of stacking single shots of color into the mold to produce a cast with different colors that do not bleed into each other.

To multi-shot, use a fine tipped item to place color within the mold. This can be basically anything, but toothpicks work very well. If you want to spend a little more money, you can use plastic luer-lock syringes with a variety of tips to inject the shot with a little more precision. If taken care of, syringes will last for as many as 10-15 shots before needing to be replaced.

Once the color has been placed, allow the cast to cure, preferably in a pressure pot. After the cast has cured, repeat the previous step as many times as needed to place different colors throughout the mold. Once you have placed all necessary colors, the last color will be the body fill. This will be the color that shows everywhere you do not have a shot already in place. After the final shot is cured, demold your cast.

Multi-shotting allows you to add a lot of detail to your sculpts, and when done correctly can result in very clean casts.

Slush casting

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Petri

The petri casting technique is a very odd technique where you use a bit of gravity and chaos theory to create vertical pillars in resin akin to Pillars of creation:

Credits: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

Comparing it to a finished Petri keycap:

The petri technique is only recommended with the use of an Epoxy Resin like Epoxacast 690 or similar. First you would need to mix up the epoxy resin as per your resins specification. You then pour the resin into the molds of your choice and wait for the right time to add drops of Alcohol Ink to the resin.

Timing is very important when petri casting because you get different effects for the different times you add the drops of alcohol ink to the resin. Below you can observe the different effects of adding ink to the resin at different times using Epoxacast 690 (time in hrs):

Once you have waited for the right amount of time, then you would add drops to the resin in the color of alcohol ink of your choice. For a 1u, no more than 2-3 drops is enough for color. Right after you add the color, you need add white. This step is important because the white alcohol ink is heavy and will fall downwards into the resin and create those pillars that petri resin is known for.

Leave some time for the alcohol ink to move around and do its dance with the resin, then gently add the mold top and place inside a pressure pot.

Cold Casting

Cold casting is a fun technique that allows you to use real metal in your casts to get an authentic shine, or possibly even a patina if you choose to.

To cold cast, the process is incredibly simple. You'll first want to get some fine metal powder of your chosen metal. Pour a small amount into your mold and close it with the stem mold. Cover the sprue holes and shake, shake, shake. Your goal is to fully coat the mold in the power, then pour the excess back into the bag.

Once the mold is fully coated, you can gently pour your resin and let it cure. For best results, you can add colors to the resin to give different effects on the final look. I find a darker color looks best with real metal powders, but experiment to see what you like.

Once your cast has fully cured, you can use a very high grit sandpaper or micromesh to very gently polish the edges, corners, and details to get that authentic metal sheen. Since the exterior is actual metal, this polish ends up looking great, as if the whole keycap were made of real metal.

At this stage, you can also add a patina or rust to your metal as well. You can find guides for the specific effect that you want online. The only thing to take care of is adding some sort of finishing coat to it to protect any aging effects you add as they can flake off over time as the metal layer is incredibly thin.