Craft, Unlimited Ideas

Intro to Polymer Clay: Koi Fish

Polymer Clay is a great stress-free material to use when creating small and vibrant sculptures.

I have had a container of polymer clay sitting in my cabinet for what feels like forever. It was an impulse purchase when I saw it on sale. I thought “I can definitely use this” and the box has been collecting dust ever since then.

But not anymore! I wanted to give the polymer clay a chance to be used. And I wanted to try my hand at a clay craft since I have not done anything with a clay medium in the last 10 years.

The first surprise that I had is that all the clay was still soft. I thought for sure it would have hardened due to just sitting out. The next surprise was how much I adored the whole process.

While my hands got a little dirty, I loved the feeling of molding the clay, finding the right tools to create texture, and looking seeing the end results (even though they aren’t exactly uniform). I decided to make koi fish because… I’m not sure, I just thought that they looked pretty, and the idea got stuck in my brain.

Check out the Craft section of MCG for more unlimited ideas. Leave a comment below and let me know what you think and how the craft works for you!


For this project, I did not really need anything besides the clay itself and some clay tools. And the clay tools I used for texture. My kit came with clay tools, so I just used what was provided.

Since I wanted to make koi fish, I went with white and black as the base of all the fish and did highlights of orange, red, and blue.


The process for making the koi fish is all the same, so I will only talk through the process of making one them. I repeated this process six times and did two fish of each color. The example process uses orange as the highlight color in the photos.

Mixing the Colors

The first step in making the koi was mixing the colors. I wanted the fish to be predominantly white with splashes of black and the highlight color. A marble approach seemed like a good idea. Or at least, I thought it was when I started.

To make the marble, I cut the clay into smaller chunks while trying to use the ratios of colors that I wanted in the mix. I just used scissors to cut the pieces of clay into smaller pieces. There was not a methodical approach this process.

I tried to disperse the colors among the clay before I rolled it into a log. I wanted the unit to be cohesive without gaps so I ended up rolling more than I anticipated that I would have to. This caused some major streaks in the clay, not the blotchy effect that I was original hoping for. But I like it!


The next step of the project was coming up with the shapes needed to great the koi fish. This required a body, two front fins, two back fins, a top fin, and eyes.

The body needs to be a long with rounded edges. One side needs to be on the larger side which then tapers down to a skinnier section. The larger side will end up being the head and the skinnier side should be the tail.

Then it is time to make the fins. All the fins ended up being the same size regardless of if they belong to the front or the back. I think that happened just due to the length of the body that was made. With a longer body, I think the back fins should have been larger.

I made elongated semi-circles for each fin at that seemed to be the best shape for them. I then made a long strip (I attempted to do a rise and fall effect that was only moderately successful) for the top fin. Lastly, I made two very, very small black circles for the eyes (too small for the camera to capture especially when working against a black surface).


Then it was time to add textures! Koi fish have scales and I wanted to do my best to simulate that in the sculptures if I could. I also wanted to capture the waviness of the fins as they have a flowy atmosphere to them.

To texture the body, I used a tool that was rounded with a lot of points on top. No idea what the tool is called. I just pricked down the back of this body in order to make little raised sections. While this is cutting into the clay, I thought it added a scale like texture for the body.

For the fins, I used a serrated knife-like tool and gently pressed into the clay. I started with making a line down the center and then fanned out the fines from there. The lines should be tight along the line of the semicircle and farther apart along the circle. This same method was used along the top fin in more of a straight line.

Assembly & Baking

Now it is time to assemble the koi fish. I attached each fin more towards the bottom of the body and use a pointed edge to push the fin into the body. I wanted to make sure they were attached.

Attaching the fin to the top of body was a little bit trickier. There wasn’t as much to work with in terms of the mass of the fin. But laying it across the top seemed to work well for what I wanted.

Lastly, I used a round tool to indent the face and create eye sockets. The fishes need a face! I then put the small round black balls into the eye sockets, one in each. And voila! It’s time to bake.

I ended up baking the clay at 230° Fahrenheit for around 20 minutes. This process was interesting because I put the clay into the oven before I turned the oven on. Turned the timer on once it reached temperature and turn the oven off and let the clay cool in the oven.


I like clay. Like more than I anticipated. There will probably be more clay projects coming up in the near future because I really enjoyed working with clay. The process was fun and simple. I do think that this craft is difficult to perfect, but it can be fun to do for any experience range. And I want to work on it more to maybe be more of an expert one day!


Polymer Clay versus Modeling Clay

There have been two types of clay that I have worked with: polymer clay and modeling clay. I used modeling clay more when I was growing up and thought it was the better medium. I don’t still feel that way.

Polymer clay is a plastic-based material that allows for hardening with a heat induced Modeling clay is an oil-based clay which can hardened when the clay is exposed to air for an extended period.

Due to these attributes, I think I always associated polymer clay as more of a craft for kids. But who says adults do not need time to do things? In fact, this allows for an extended workability time to get those details just right. And there are so many colors that polymer clay comes in!

Quick Recipe

Polymer Clay Koi Fish

Polymer Clay is a great stress-free material to use when creating small and vibrant sculptures.


  • 1 Part Orange Clay
  • 1 Part Black Clay
  • 3 Part White Clay


  • Portion out the clay by color (3 parts white, 1 part black, 1 part orange). Cut the clay into small chunks and mix together.
  • Roll the clay chunks into one ball. Cut into 6 parts, 4 small, 1 even smaller, 1 larger.
  • Shape the largest piece into a log with one large section and one skinny section. Shape the small pieces into four flat semi-circles. Shape the smallest piece into a long flat line.
  • Using a serrated tool, texture the bad of the large piece, create lines on the small semi-circles, and create lines on the long flat piece.
  • Attache the semi circles to the large piece. Attach the long flat piece on the top of the large piece.
  • Bake as per the clay instructions.

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