◆ Resin
Heart resin keychain mold
Nine heart resin keychain blanks per pour, each with a hole for the key ring. Silicone you pour yourself.
◆ Resin
Nine heart resin keychain blanks per pour, each with a hole for the key ring. Silicone you pour yourself.
A silicone mold for nine heart-shaped resin keychain blanks, each 50 x 43 mm and 5.5 mm thick with softly rounded edges. A small post under the cleft of every heart leaves a 3.8 mm hole for the jump ring, so the blanks come out ready to hang, with no drilling.
Made with our tray mold generator in its flexible silicone tray mode: print the caster, pour silicone into it and peel out a flexible nine-heart mold. Resin releases from silicone with a gloss and no release agent, and each blank takes about 8 ml, so one small batch of resin fills the whole tray.
Heart keychains are the classic resin gift for Valentine's Day, weddings and Mother's Day, with glitter, a photo or a name inside. The zip carries the printed caster exactly as the tool exported it, one heart 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 pink resin hearts in front, not a photo.
Print the caster as exported, open side up, no supports. For glassy blanks, print with ironing on the top surfaces, or sand the raised shapes smooth and brush on XTC-3D: the silicone copies every layer line and resin shows it.
Mix 230 ml of silicone, ideally a platinum one, 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 and peel it out. Each cavity has a small post that leaves the key ring hole.
Mix epoxy casting resin at the ratio on the bottle, stir slowly for three minutes and let it rest a few minutes so the bubbles rise. Glitter, mica or dried flowers go in face down: the side against the silicone is the front.
Fill each cavity to just below the top of its post (about 8 ml each) so the hole stays open, and pass a heat gun or a lighter quickly over the surface to pop the bubbles. Cover the tray against dust.
Leave epoxy 24 hours, then flex the tray and peel it off the blanks rather than pushing them out. Let them harden two more days, then fit a 6 to 8 mm jump ring and a key ring.
Print details
| Cast material | Resin |
|---|---|
| Printed parts | 1 |
| Size (W x D x H) | 171 x 149 x 15 mm |
| Print bed needed | 172 x 149 mm, 15 mm tall |
| Filament | ~100 g |
| Layer height | 0.2 mm |
| Infill | 15% |
| Supports | Not needed |
| Download | ZIP: printed caster (STL) + one keychain blank (STL) + tool master (STL) + print and pour sheet |
| Added | 2026-09-26 |
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 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.
Print the photo on ordinary paper, cut it to the heart and seal both sides with a thin coat of Mod Podge or clear tape so the resin cannot soak in and turn it grey. Pour 2 mm of resin, let it gel, lay the photo face down and fill to just below the post.
The front is the side against the silicone, and the silicone copied the printed caster, layer lines included. Sand the raised hearts smooth or coat them with XTC-3D before pouring the silicone. Moisture clouds epoxy too, so pour in a dry room above 20 C.
Each heart takes about 8 ml, so the full tray of nine needs about nine times that, plus a little for what stays in the cup. Mix slightly more than you need: topping a cavity up from a second batch leaves a visible line inside a clear heart.
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