Make: Clay Sea Slugs – A Color and Form Art Project for Kids

Use air-dry clay and watercolors to sculpt your own bold and exotic clay sea slugs with air-dry clay or playdough. An ocean-themed or summer art invitation for kids with so much room for creativity!

Our clay sea slugs sitting on a white background

I don’t remember exactly when I first learned about Nudibranchs (“sea slugs” for us oceanography amateurs) but what I do recall is their incredible array of lush colors and the cool variations of their forms caught my eye immediately. For years they’ve been inching their way around the edges of my art-making mind, and this week we finally had some time to bring a few to life with a bit of modeling clay and some watercolors.

Our clay sea slugs art project air-drying on cardboard strips

With over 2,000 species of wildly colorful Nudibranchs, there is no shortage of visual inspiration for this art project! And an air-dry clay base lends itself well to experimentation of form AND color through the use of hand-sculpting and simple watercolor washes.

Our clay sea slugs sitting on a white background

There are a few choice qualities sea slugs possess that make them perfect for interpretation through kids’ art. Their shapes provide a wonderful opportunity for kids to embrace playing with clay, and Nudibranchs have been found in countless brilliantly wild color combinations. Combine both of these features, and you have an art project that invites SO MUCH creative interpretation.

Take a peek at our own clay nudibranchs drying in the sun…

For more sculpting fun visit our salt dough starfish, creative soft sculpture creatures, or Memphis-style paper sculptures

To make your own clay sea slugs you can use:

Note: We prefer to shop locally or use what we have at home, but this list contains Woodpeckers Crafts, Etsy, Blick Art Materials, and/or Amazon affiliate links for reference. As Amazon Associates, we make a small commission on qualifying purchases.*



  • A small bowl of water
  • Acrylic or tempera paints
  • Small spray bottles or a sponge
  • A hairdryer (to speed up paint drying time)
  • Gloss Mod Podge (like this)
  • Feathers or other decorative arts & crafts materials

Clay Sea Slugs Kids Art Project Instructions:

  1. Begin with 3 or 4 small blocks of clay

    The blocks of clay we started with below were about 1 inch wide, 1 inch tall, and 3-4 inches long.
    White air dry clay sitting on a cookie sheet
    I like using old cookie sheets as a workspace (especially for clay, as they don’t soak up any of the moisture while sculpting) but all you need is a clean, flat, smooth surface.

  2. Form your clay into sea slug shapes

    More than anything, the point here is to PLAY with your clay – roll it around, form it into rounded amorphous shapes, stretch it into long flat lines – get a real feel for it!
    The first step of making our air dry clay sea slugs
    Once you have mushed around the clay a bit (“mushed” IS a technical term, I’m sure) try sculpting it into sea slug-like forms. You can use pictures for reference, but don’t get too caught up in making your forms exact – as you’ll find, sea slugs take on ALL kinds of shapes. You can also try making your sea slug look like its in motion. Form the body into a curve, raise a section, or give it a wavy bottom.

  3. Experiment with textures

    Sea slugs come in all shapes, sizes, AND textures – some look incredibly smooth, some have spiny gills, and other look like they’re covered in feathery hairs. Use clay tools, building blocks, a small rolling pin, or plastic silverware to add texture.
    Adding texture to our clay sea slugs with plastic silverware

  4. Add sea slug details

    Reference some pictures of nudibranchs, and you’ll see that they have cerata (those are groups of long, anemone-like structures) rhinophores (the 2 horn-shaped antennae-like parts) feathery gills, or plumes (raised circles).
    Our clay sea slugs art project air-drying on cardboard strips
    Look around to find some small items you already have at home to recreate those parts. We took apart a pinecone to use the scales, cut apart q-tips, and broke toothpicks in half, but there are so many other options once you start looking!

  5. Let air dry for 24-72 hours

    Let your clay air dry for at least 24 hours. You’re looking for it to be bone dry – dry to the touch on the top AND bottom.
    Our clay sea slugs art project air-drying on cardboard strips

  6. Paint with watercolors

    Start painting! Watercolors work perfectly for this project and especially well with the white modeling clay. Experiment with blending colors, or wash your entire project with water then blend lots of colors together. Use a q-tip to dab bright spots onto the wet paint. The possibilities are endless, so take the opportunity to play!
    Painting our clay sea slugs
    On this kind of clay, watercolors are extremely forgiving, so you can keep a paper towel or sponge and an extra bowl of water on hand – if you feel like you dislike a choice you’ve made, simply wash it with clear water and wipe with your paper towel or sponge.

  7. Let dry

    Let your watercolors dry. Ours soaked in fairly quickly (within about 40 minutes) but you can use a hairdryer on a low heat setting to speed up the process.
    Painting our clay sea slugs

  8. Add details with acrylic or tempera paints (optional)

    The elements we added (like the q-tips and pinecone scales) don’t show off the bright watercolors in the same way the white clay does, so we opted to add some brighter color with acrylic paint.
    Painting our clay sea slugs
    This is totally optional, so you can skip it OR grab a small brush, q-tip, or other mark-maker to add more personality to your nudibranchs. On a couple of our sea slugs, we used the spray bottle acrylic spray paints we had made for our fireworks art project (an easy process for kids) and loved the effect!

  9. Glaze with Mod Podge or similar (optional)

    This is an optional step, but it gives the clay sea slugs that slimy shine that helps us imagine they just wriggled up out of the ocean.
    Painting our clay sea slugs
    Use a small paintbrush to brush on a coat of Mod Podge, then let dry. When using Mod Podge, drying to the touch typically takes about 25 minutes, curing (a hard coat that’s fairly waterproof) typically takes about 2 weeks.

Beyond a deep sea-themed clay project, I can absolutely see these being used as a Halloween art invitation. Maybe it’s just that I’ve been catching up on the latest season of Stranger Things, but the unstructured fluidity of the forms totally reminds me of alien-like sci-fi creatures. I mean, we are practically one color palette choice away from a crew of tiny army of baby Demogorgons.

Our clay sea slugs sitting on a black background

Variations on our clay sea slugs

I absolutely love the way our painted clay Nudibranchs turned out, but there are endless ways to alter this process for younger kids, occasions when you have less prep time or less permanent results…

  • Make playdough sea slugs. Instead of using clay and adding paint, grab a few colors of playdough, similar texturing supplies, and make some temporary sea slug sculptures.
Our clay sea slugs art project air-drying on cardboard strips

Summer swim-themed playdough invitation, build indoor sandcastles with our DIY moon sand, or create imaginative playdough fairy forests,

*A note about affiliate links: We strive to use simple, earth-friendly supplies that can be purchased locally whenever we can, but sometimes we find the best universally available options, a rare eco-friendly find, or a niche product only available on Blick Art Materials, Amazon, Etsy, or Woodpeckers Crafts. When included in our supply list, these products are affiliate links, and if you click through to make a purchase we receive a small commission that helps us re-order these supplies!

Amanda Eldridge
Amanda Eldridge

With a passion for cultivating imagination, Amanda aims to help kids and families discover their creative potential through art, play, adventure, activism, conservancy, and community. Amanda has a background in graphic design, environmental design, and art curation. When not playing with ideas and designs for barley & birch, she enjoys working in freelance design, art, and illustration.


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