◆ Resin

Round resin coaster mold

Two 96 mm round resin coasters per pour, 7 mm deep, with a softly rounded top edge. Silicone you pour yourself.

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3D render of the printed caster for a two-cavity round resin coaster mold, with three glossy ocean blue round resin coasters in front
Resin ~117 g

A silicone mold for round resin coasters 96 mm across (3.8 inches) and 7 mm thick, two to a tray, sized so the caster for two still prints on a 220 mm bed. The top edge of each coaster is rounded 2.5 mm, so it comes out of the mold with a soft, glossy rim that needs no sanding, and the back is the flat face you pour from.

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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. Resin releases from platinum silicone with a mirror face and no release agent, and a flexible mold peels off a coaster without the stress that cracks a thin edge. Each coaster takes about 50 ml of resin.

Round coasters are the classic resin project: ocean waves, petri dish cells, dried flowers, geode crystals or a simple marbled pour, and a set of four makes a gift. At 7 mm, use a deep-pour casting resin in one go, or a coating resin in two or three 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 ocean blue resin coasters in front, not a photo.

Round 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 215 ml of platinum silicone (mix it in one batch)
  • About 50 ml of deep-pour or casting epoxy per coaster
  • Pigment, mica, alcohol ink, or pressed flowers
  • Nitrile gloves, a heat gun or torch, a level surface 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 215 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 50 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

3 h 50 minPrint time
~117 gFilament
1Printed parts
108 × 210 × 19 mmSize (W x D x H)
All print details
Print details
Cast materialResin
Printed parts1
Size (W x D x H)108 x 210 x 19 mm
Print bed needed210 x 108 mm, 19 mm tall
Filament~117 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
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.

Download free on Thingiverse

Free download. Opens the Thingiverse listing in a new tab.

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 make an ocean wave resin coaster in the round mold?

Pour a blue layer with a little white at one edge, let it gel for 20 to 40 minutes, then add a thin line of white resin along the edge of the blue and blow it gently with a heat gun on low: the white spreads into lacy cells that read as surf. Sand or beige resin on the other side makes the beach.

Are the round resin coasters safe for hot mugs?

Warm mugs are fine once the resin has cured for a full week. Most epoxies soften again at 50 to 60 C, so a mug straight from the kettle can leave a ring. For hot drinks, pick a resin that states a heat resistance of 100 C or more, and add cork or felt pads to the back.

Why did my round coaster come out with a dip in the middle?

Resin shrinks slightly as it cures and pulls in from the walls, which leaves the poured back a touch concave. It does not matter on the back of a coaster, but you can top it up with a thin second pour after 24 hours, or sand the back flat and add felt pads so it sits level.

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