◆ Crayons

Rainbow crayon mold

Eight rainbow crayons on clouds, with a groove between every band. Melted from broken crayons in the oven.

Make your own tray mold
3D render of the printed caster for an eight-cavity rainbow crayon mold, with three yellow rainbow crayons with five bands on two clouds in front
Crayons ~140 g Pro early access

A silicone tray for eight rainbow crayons, each 60 x 35 mm and 12 mm thick: five arched bands sitting on two puffy clouds, with a fine groove between the bands and around each cloud. About 16 ml each, and the arch colours nicely with its edge or its flat back.

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Made with our tray mold generator in its flexible silicone tray mode: print the caster, pour a heat-proof platinum silicone into it and peel out the tray. The crayons melt in that silicone in the oven; the printed caster never goes near it.

The ridges in the mold mark the bands, so you can lay a different colour of crayon pieces in each band before it goes in the oven and get a striped rainbow, or melt one colour and let the grooves do the work. The zip carries the printed caster exactly as the tool exported it, one rainbow 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 yellow rainbow crayons in front, not a photo.

What you need

3
  • About 265 ml of platinum silicone rated for 200 C (400 F) or more
  • Broken wax crayons in rainbow colours, peeled, about 16 ml per rainbow
  • A baking sheet, a skewer and oven mitts

How to cast it

6

  1. Print the caster as exported, open side up, no supports. It never goes in the oven: PLA softens at about 60 C.

  2. Pour 265 ml of a platinum silicone rated for 200 C (400 F) or more into one corner in a thin stream, letting it rise over the shapes to the rim. Tap out the bubbles, let it cure and peel it out: that silicone is the crayon mold.

  3. Soak old crayons in warm water for ten minutes, peel off the paper and break them into pieces about 1 cm long. Sort them by colour, or mix colours for swirled crayons.

  4. Set the silicone tray on a baking sheet. Lay small pieces band by band, red on the outside to purple on the inside, and white or grey in the clouds. Fill to the top and heap it a little: the pieces shrink as they melt.

  5. Bake at 230 to 275 F (110 to 135 C) for 10 to 20 minutes, until every piece has melted. Hotter makes the wax separate into a white film on top.

  6. An adult lifts the sheet out. Let the crayons cool for 30 minutes, give the tray 10 minutes in the freezer, then flex it and pop them out. Keep this tray for crafts, never food.

Print details

4 h 40 minPrint time
~140 gFilament
1Printed parts
136 × 163 × 21 mmSize (W x D x H)
All print details
Print details
Cast materialCrayons
Printed parts1
Size (W x D x H)136 x 163 x 21 mm
Print bed needed164 x 136 mm, 22 mm tall
Filament~140 g
Layer height0.2 mm
Infill15%
SupportsNot needed
DownloadZIP: printed caster (STL) + one crayon (STL) + tool master (STL) + print and pour sheet
Added2026-09-26

Pro early access until October 26, 2026, then free with any account.

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 keep the colours of the rainbow crayon from mixing?

Use small pieces, lay each colour in its own band, and melt at the low end, about 230 F (110 C). Take the tray out the moment the last piece is liquid and do not move it until the wax has set, since sloshing is what blends the bands.

Can I make rainbow crayons in one colour instead?

Yes, and they still read as rainbows: the grooves between the bands and round the clouds show on the finished crayon. One-colour rainbows are quicker, never turn muddy, and a set of eight in different colours makes its own rainbow.

What else can the rainbow crayon mold make?

Soap, wax melts and, in a separate tray poured in food-safe platinum silicone, chocolate or candy melts. Keep the tray you use for crayons for crafts only, because crayon pigment stays in the silicone.

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