◆ Clay

Pumpkin slip casting mold

A four-piece plaster mold for slip casting an eight-lobed pumpkin votive or jar, 110 mm across.

Make your own plaster slip-cast mold
3D render of four printed plaster-mold housings for a pumpkin, orange and blue shells beside charcoal bases, with an orange fired eight-lobed pumpkin in front
Clay ~4568 g Pro early access

A squat pumpkin 110 mm across and 86 mm tall once fired, with eight rounded lobes and a round 48 mm collar at the top where the stem would be. Drop a tea light in, or make a lid and it is a jar. It holds 333 ml to the brim.

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Made with our plaster mold generator: a printed housing per plaster piece, you pour the plaster, and the plaster is the mold. The lobes bulge over the valleys, so the page's seam check found about 3% of one piece stuck at two pieces, 2% at three and nothing at four: it is a four-piece mold with every seam in a valley. It casts through the collar, and the mold is cut 15% oversize for a 13% shrinkage slip.

Pumpkins sell from September to Thanksgiving, in white, orange and speckled glazes alike. The zip carries the four bases, one shell and clamp set that fits all four, the pumpkin as its own STL, the tool's print sheet and a recipe file for the generator.

Shown as a 3D render of the printed bases and shells with the fired piece in front, not a photo.

What you need

5
  • About 780 ml of casting slip to fill the mold (most of it pours back out)
  • Pottery plaster (No. 1 Pottery or similar), enough to fill each housing to the top of its shells
  • Mold soap or petroleum jelly, and strong rubber bands or mold straps
  • A pencil to number the plaster pieces
  • Clay for a stem or a lid, if you want one

How to cast it

9

  1. Print the 4 bases and the one set of shells and clamps, no supports. The sheet in the zip asks for 4 or more walls and 40% gyroid, because the shells get clamped.

  2. Stand the two shells round the first base, slide the clamps over the ends, and run a thin bead of petroleum jelly along every seam. Brush mold soap over the printed master slice and the natch sockets so the plaster lets go.

  3. Sift pottery plaster into water (about 100 g of plaster to 70 g of water), let it slake for two minutes, mix for three, then pour it up to the top of the shells and tap the housing to lift the bubbles.

  4. After 30 to 45 minutes, when the plaster is warm and hard, unclamp, lift the shells off and ease the plaster piece off the base. Move the same shells and clamps to the next base and pour again.

  5. Let the plaster pieces dry for about a week somewhere warm and airy, until they feel light and no longer cool to the touch. A damp mold barely takes water out of the slip.

  6. Band the 4 pieces together with the natches seated, stand the mold mouth up and fill it to the top of the collar with slip. Top it up as the level drops.

  7. When the wall is 3 to 4 mm thick (usually 10 to 20 minutes, check at the rim), pour the slip back out and leave the mold upside down to drain.

  8. Once the cast loses its shine and pulls away from the plaster, trim the rim, open the mold and lift the piece out. Dry it slowly to bone dry, then bisque and glaze fire.

  9. For a stem, roll a short coil, twist it, and join it on a slab lid that sits in the collar, or on the collar rim itself, at leather hard.

Print details

152 h 20 minPrint time
~4568 gFilament
8Printed parts
207 × 203 × 118 mmSize (W x D x H)
All print details
Print details
Cast materialClay
Printed parts8
Size (W x D x H)207 x 203 x 118 mm
Print bed needed203 x 169 mm, 118 mm tall
Filament~4568 g
Layer height0.2 mm
Infill40%
SupportsNot needed
DownloadZIP: 4 bases + one shell and clamp set (8 printed parts, STL) + pumpkin master (STL) + print sheet + recipe
Added2026-09-25

Pro early access until October 25, 2026, then free with any account.

Make your own plaster slip-cast mold →

Made with the free Plaster slip-cast mold generator. Upload your own model and get the same kind of mold built around it, in your browser.

Free for personal use. Selling the pieces you cast needs a commercial licence (Pro or Founder); passing on the file itself is not permitted on any plan. Full terms.

New to casting? Read the plaster mold guide.

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Questions about this design

Why does the pumpkin mold need four pieces?

Each lobe curves back in toward the valleys on either side of it. With two or three pieces, some lobes sit across a seam and hook the plaster as it comes off. With four, all eight seams fall in valleys and every lobe lifts straight out.

How do I add a stem to the ceramic pumpkin?

Make a small slab lid that sits inside the 48 mm collar and join a twisted coil stem to it at leather hard, or join the stem straight onto the collar rim for a closed pumpkin with a vent hole. Score and slip both joints.

Can the pumpkin hold a real candle?

A tea light, yes, once it is fired: stoneware and porcelain take the heat without trouble. Leave the collar open so the flame gets air, and glaze the inside so wax spills wipe out.

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