◆ Resin

Agate slice resin coaster mold

Two agate slice resin coasters per pour: an irregular stone outline 112 x 90 mm, 7 mm deep. Silicone you make.

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3D render of the printed caster for a two-cavity agate slice resin coaster mold, with three glossy purple irregular stone shaped resin coasters in front
Resin ~122 g Pro early access

A silicone mold for agate slice resin coasters about 112 x 90 mm and 7 mm thick, two to a tray. The outline wanders like a cut stone slice, with no dent deep enough to trap air, and the top edge is rounded 2.5 mm so the coaster comes out with a glossy rim ready for a line of gold paint.

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Made with our tray mold generator in its flexible silicone tray mode: print one part, a caster, pour a platinum silicone into it and peel it out. That silicone is the coaster mold, and resin lets go of it with a mirror face and no release agent. Each coaster takes about 52 ml of resin.

Agate and geode coasters are among the most searched resin projects, and most molds sold for them are round. Pour rings of colour from the edge inward, or build a crystal centre from crushed glass. At 7 mm, use a deep-pour casting resin, or a coating resin in thin layers. The zip carries the printed caster exactly as the tool exported it, one coaster on its own as an STL, the master uploaded to the tool, and a print and pour sheet with the silicone figure the tool measured.

Shown as a 3D render of the printed caster with three purple resin agate slice coasters in front, not a photo.

Agate slice resin coaster mold at a glance: every printed part with its size, print time, filament, print settings and the three steps to use it

What you need

4
  • About 239 ml of platinum silicone (mix it in one batch)
  • About 52 ml of deep-pour or casting epoxy per coaster
  • Two or three pigments, white and a metallic mica, crushed glass if you want crystals
  • Gold leafing pen, nitrile gloves, a heat gun and cork or felt pads

How to cast it

6

  1. Print the caster as exported, open side up, no supports. Turn on ironing for the top surfaces, or sand the raised shapes smooth and brush on XTC-3D: the silicone copies every layer line, and resin shows each one on its glossy face.

  2. Mix 239 ml of platinum silicone and pour it into one corner of the caster in a thin stream until it covers the shapes to the rim. Tap out the bubbles, let it cure as long as its datasheet says and peel it out. That silicone is your resin mold: platinum silicone gives resin a glossy face and needs no release agent.

  3. Set the mold on a level surface in a ventilated room, gloves on. A 7 mm coaster is a job for a deep-pour or casting epoxy in one pour. A coating (tabletop) epoxy is made for 3 mm or so: pour it in two or three layers, each once the last has gelled, or it overheats and yellows.

  4. Mix about 52 ml per coaster, stir slowly for three minutes, add colour, mica or inclusions, and pour each cavity level with the rim. Remember the side against the silicone is the top of the coaster.

  5. Pass a heat gun or torch over the surface after five minutes and again after fifteen to pop the bubbles, then cover the mold against dust and leave it 24 to 72 hours, as long as your resin says.

  6. Flex the mold and peel it off the coaster. Sand the back flat if it has a lip, add cork or felt pads, and let the coasters cure a full week before a warm mug goes on them.

Print details

4 hPrint time
~122 gFilament
1Printed parts
124 × 195 × 20 mmSize (W x D x H)
All print details
Print details
Cast materialResin
Printed parts1
Size (W x D x H)124 x 195 x 20 mm
Print bed needed195 x 125 mm, 20 mm tall
Filament~122 g
Layer height0.2 mm
Infill15%
SupportsNot needed
DownloadZIP: printed caster (STL) + one coaster (STL) + tool master (STL) + print and pour sheet
Added2026-09-27

Pro early access until October 27, 2026, then free with any account.

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Make your own tray mold →

Made with the free Tray 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 ice cube tray mold guide.

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Questions about this design

How do I get agate bands in the agate slice resin coaster?

Mix three or four shades of one colour plus white. Pour the darkest around the edge first, then each lighter shade just inside the last, and finish with clear or white in the middle. Drag a toothpick lightly through the rings to make them wobble, and let the resin level on its own.

How do I paint the gold edge on an agate coaster?

Once the coaster is fully hard, run a gold leafing pen or a small brush with gold liquid leaf round the rounded rim, holding the coaster on its side. Two thin coats look better than one thick one. Seal with a clear spray, or the gold rubs off where hands touch it.

Can I make a geode centre in the agate coaster mold?

Yes, and it is easier face down than in an open slab. Put crushed glass or small crystals in the middle of the empty cavity first, pour a little clear resin over them, then pour the coloured bands from the edge. When you flip the coaster, the crystals sit in the glossy front.

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