Introduction: 🥧The Pi(e) Equation: a Pi-Pie Inspired Chocolate Gift 🥧

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About: I am a passionate industrial designer that loves to create all kind of things. I also studied some semesters of Robotics at the university. I love learning and teaching as well. If you have any questions about…

I wanted to bring together my love for design, modeling, crafting, and sweets into one delightful surprise: a jar topped with a realistic mini pie that hides math-inspired chocolates 🧁➕🔢

The result? A playful fusion of art, baking aesthetics, and math geekery — perfect for Pi Day, a nerdy gift, or simply to celebrate creativity.

Follow each step carefully to create your own punny pie filled with symbolism (and chocolate)!

Supplies

  1. 1 round jar with a twist-off lid
  2. Modeling clay
  3. Small drill or rotary tool
  4. Thin wire
  5. Acrylic paints (red, reddish-violet, sandy beige, white, brown, black)
  6. UV resin and UV lamp
  7. Glitter or mica powder (optional, for the shiny filling look)
  8. Silicon brushes and/or clay modeling tools
  9. Autodesk Inventor (or any 3D modeling software)
  10. 3D printer
  11. Mold-making silicone
  12. Disposable cup
  13. Small screwdriver
  14. Chocolate and white chocolate for melting
  15. Water
  16. Small pot and bowl for double boiling
  17. Refrigerator

Step 1: 🥧Preparing the Jar Lid

I used a round jar with a twist-off lid — the circular shape felt perfect for a pi-inspired pie!

I drilled six small holes into the lid using a rotary tool and a fine drill bit. The holes were arranged in three pairs, spaced evenly near the edge.

I then inserted small pieces of wire into each pair of holes, twisted them a few times, and left the ends sticking out. These wires will hold the pie topper firmly in place later on.

Step 2: Adding the Pie Texture

I kneaded some modeling clay and pressed it onto the lid, creating a rough, bumpy surface to mimic the texture of a real pie.

Using a clay-sculpting tool, I added more defined details to enhance the rustic, homemade look.

Step 3: 🎨Painting the Filling Base

Once the clay had dried completely, I painted the entire surface with red and reddish-violet acrylic paints. This creates the base for a juicy fruit filling look.

Step 4: 🍓Resin for a Juicy Look

After the paint dried, I mixed UV resin with a bit of shiny powder pigment and gently spread it over the top.

I then cured the resin under a UV lamp. This gives the filling a glossy, fruity sauce-like effect that catches the light beautifully. 🍓

Step 5: Designing the Pi Cutter

Using Autodesk Inventor, I designed a cookie cutter in the shape of the Pi symbol (π).

To do this, I pasted the Pi character into the “text” feature and tried different fonts until I found one I liked.

I extruded the symbol, hollowed it out from both the top and bottom, leaving 0.4 mm walls (to match my 3D printer nozzle size), and added a grip around the edges.

Step 6: 3D Printing the Pi Cutter

I exported the file as an STL and 3D printed my Pi-shaped cutter.

Step 7: Designing the Wavy Edge Cutter

To create a more accurate and reusable edge for the pie, I designed a second cutter with a curved, wavy border using Inventor.

While this part could be cut manually, I preferred the precision (and reusability) of a custom cutter.

Step 8: Designing the Inner Circle Cutter

I also created a circular cutter to define the inner edge of the border of the pie.

Step 9: Creating the Lattice Strips

I rolled out more modeling clay and cut thin strips — almost like little pasta ribbons.

Then I wove them together just like a traditional pie crust lattice.

Step 10: Shaping the Lattice Top

I placed the circular cutter over the woven lattice, not to cut directly, but to mark the area.

Using a clay tool, I carefully cut around that circle.

Step 11: Adding the Pi Symbol

I used the Pi cutter to cut out a symbol from the center-top area of the lattice.

Then I placed the woven crust with the Pi cutout onto the jar lid — now painted and coated in glossy resin.

Step 12: Smoothing the Underside

I added small bits of modeling clay beneath the Pi shape and smoothed them out with a silicone brush and a little water.

Step 13: Pie Crust Border

I flattened more modeling clay and cut a circular piece for the base.

I placed it over the lid and used a clay tool to gently texture the outer edge, simulating a pie crust border.

Step 14: Cutting the Decorative Edge

Using the wavy-edge cutter I designed earlier, I trimmed the border.

Step 15: Giving It Character – Eyes and Smile

To add a cute face to the pie, I created two small holes for eyes and used a bent paperclip to carefully press in a simple smile. 😊

Step 16: Enhancing the Texture

I added more texture to the border using a modeling tool, giving the crust extra dimension and a more baked look.

Step 17: 🎨Base Paint Layer

Once the clay was fully dry, I painted the entire surface using a sandy beige color mixed with a bit of white.

This gave it a soft, pastry-like appearance.

Step 18: Shading for a Baked Look

Using a sponge with very little paint, I dabbed sandy beige over the top of the pie crust.

Then I added a touch of brown in the same way to give it a toasty, baked finish.

Step 19: Finishing the Face

I made two small balls of modeling clay for the eyes, placed them into the holes created earlier, and painted them black, same for the smile.

Step 20: 🔢Designing the Chocolate Molds

In Inventor, I created 3D designs for chocolates in fun math-inspired shapes: the Pi symbol, the digits of Pi, circles, and an infinity sign.

I extruded them and added open-box outlines around them to use as mold frames.

Step 21: Printing the Chocolate Shapes

I exported the mold files as STL and printed them in 3D.

Step 22: Measuring the Needed Silicone

I filled the printed mold with water and poured it into a disposable cup.

I marked the water level on the cup, then dried both the mold and the cup completely.

Step 23: 🧪 Mixing the Silicone

I made a second mark at the halfway point between the bottom of the cup and the water line.

Then I poured silicone part A up to the first mark, and silicone part B up to the second mark.

(Note: The ratios may vary depending on the brand of silicone used, always follow your supplier's instructions!)

Step 24: Releasing the Mold

The next day, once fully cured, I removed the silicone mold. I gently loosened the edges using a small flathead screwdriver, then pulled it out by hand.

Step 25: 🍫 Making the Chocolates

I melted chocolate in a double boiler and poured it into the silicone mold.

After 15 minutes in the fridge, I repeated the process with more chocolate — this time including white chocolate too.

Step 26: Assemble and Delight!

Once everything is dry and set, place your chocolates inside the jar and screw on the pie lid.

Now you’ve got the perfect Pi(e) Day surprise — a geeky, sweet gift with a clever twist.