◆ Resin
Alphabet resin keychain mold, A to I
Nine bubble letter keychains, A to I, each with its own key ring hole. From a silicone mold you pour yourself.
◆ Resin
Nine bubble letter keychains, A to I, each with its own key ring hole. From a silicone mold you pour yourself.
A silicone mold for nine chunky letter keychains, A, B, C, D, E, F, G, H and I, in a rounded bubble typeface 35 mm tall and 5.5 mm thick. Each letter carries a round tab on top with a small post in the cavity, so every letter comes out with a clean 3.8 mm hole for a jump ring and nothing to drill.
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 resin mold. Resin lets go of platinum silicone with a glossy face and needs no release agent, which a printed mold never gives you. The whole set of nine takes about 43 ml of resin.
Initial keychains are the resin best seller for gifts, bridesmaids and bag tags, and this is the first of three trays that make the whole alphabet (J to R and S to Z and & are separate designs), plus a 0 to 9 number tray. The zip carries the printed caster exactly as the tool exported it, the nine letters on their 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 the nine pink resin letters in front, not a photo.
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.
Mix 199 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.
Work in a ventilated room with nitrile gloves on. Mix epoxy casting resin exactly at the ratio on the bottle, stir slowly for three minutes scraping the sides, 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 (all nine letters take about 43 ml together) so the hole stays open, and pass a heat gun or a lighter quickly over the surface to pop the bubbles. Cover the mold against dust.
Leave epoxy 24 hours (UV resin: cure each layer under the lamp), then flex the mold and peel it off the pieces rather than pushing them out. Let epoxy harden two more days before you fit jump rings, hooks or a tassel.
Print details
| Cast material | Resin |
|---|---|
| Printed parts | 1 |
| Size (W x D x H) | 122 x 153 x 18 mm |
| Print bed needed | 153 x 123 mm, 18 mm tall |
| Filament | ~84 g |
| Layer height | 0.2 mm |
| Infill | 15% |
| Supports | Not needed |
| Download | ZIP: printed caster (STL) + one set of nine letters (STL) + tool master (STL) + print and pour sheet |
| Added | 2026-09-27 |
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.
Twenty-six letters at a size that reads as a keychain would need a caster far bigger than a 220 mm print bed. Nine letters to a tray keep each caster printable on any common printer and each silicone pour small, and you only pour the trays for the letters you actually sell most.
Pour the tray twice, or pour a second silicone mold from the same caster: the caster is reusable and a second copy of the tray costs only the silicone. Sellers usually keep two or three copies of the tray for vowels and the most popular initials.
Yes. Pour a clear or glitter letter, let it cure, then add a small vinyl name or a date on the flat back and seal it under a thin coat of resin. For a hidden message, pour half the cavity, let it gel, lay printed text face down and fill to just below the post.
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