How to make a custom ice cube tray mold (multi-cavity)
A store-bought tray makes one boring rectangle, in one fixed grid, forever. A custom multi-cavity tray mold lets you batch out any shape you can model - cubes, spheres, hearts, logos, skulls - a whole grid at a time, and reuse it for far more than ice. Meshcast builds you a rigid printable tray plus a matching flexible silicone caster, so the same mold pours ice, chocolate, gummies, wax melts and resin embeds. This guide walks through designing it, printing it and casting with it, and the multi-cavity tray generator lays out the whole grid for you in seconds.
What a multi-cavity tray mold is
A multi-cavity tray is a single mold with a grid of identical cavities, so you fill and release a whole batch at once instead of one piece at a time. Meshcast gives you two parts that work together: a rigid printed tray (the structure and former) and a flexible silicone caster you cast inside a printed shell. The rigid part keeps everything dimensionally true and freezer-stable; the flexible part is what you actually fill and flex to pop pieces out - no twisting, no prying, no broken corners.
- Pick a shape & cavity count. Choose a built-in cube/sphere/heart or your own STL, and decide how many cavities the grid holds.
- Generate the tray & caster - a rigid tray and a matching shell to cast the flexible insert.
- Print the parts in PLA or PETG, no supports.
- Cast, fill & flex - pour silicone for the caster, then fill it with whatever you like and flex out the results.
Why print your own tray
A printed tray gives you any shape, any cavity count, any size - not the one layout a shop sells. You can match the cavity size to your glassware, fit the grid to your freezer drawer, and print spares so a big batch goes faster. Because the cavities come off one generated grid, every piece is the same size, which matters if you're portioning chocolate, dosing gummies, or selling wax melts by weight. And one tray serves many crafts: it's an ice tray, a chocolate mold, a gummy mold and a wax-melt clamshell all at once.
What you'll get
- A rigid multi-cavity tray that holds the whole grid square and stable.
- A printed shell to cast a flexible silicone caster from - the food-safe, flexible part you fill.
- True-millimetre sizing - set the cavity dimensions and grid, and the generator sizes the tray and caster to match, ready to slice.
What you'll need
- Filament: PLA is fine for the tray and shell; PETG is a small upgrade if you want extra toughness for repeat use.
- Food-safe silicone: platinum-cure (addition-cure), FDA CFR 21 177.2600 or LFGB rated, for the flexible caster you fill with food.
- Your medium: filtered water for ice, melted chocolate or candy melts, gummy mix, wax for melts, or resin/plaster for embeds.
- A scale and mixing cups for accurate silicone ratios and repeatable batches.
Step by step
Pick a shape and cavity count
Open the multi-cavity tray generator, pick a built-in cube/sphere/heart or drop in your own STL, and set how many cavities you want and how they're laid out. Set the cavity size in real millimetres to match your glass or your portion size. Preview the grid on the virtual print bed and check the overall tray fits your print volume before downloading STL or 3MF.
| Setting | Suggested |
|---|---|
| Small cube cavity | 25–35 mm |
| Whisky sphere cavity | 50–60 mm |
| Grid for small cubes | 3×4 or 4×4 |
Generate the tray and the caster shell
The generator outputs a rigid tray and a matching shell you cast the flexible silicone caster inside. If you only need rigid casting (wax, plaster, simple shapes) you can use the tray alone; for clean food-safe release of detailed shapes, cast the silicone caster too. Download both parts.
Print the parts
Slice the tray and shell at 0.2 mm (or 0.12 mm for an extra-smooth cavity) with 3 walls and 15% infill. No supports - the parts are designed to print cavity-up. The cavity surface becomes the cast surface, so keep the first layers clean. Print the tray and shell on the same plate so they cool to matching dimensions.
Cast the flexible silicone caster
Weigh food-safe platinum-cure silicone exactly per its data sheet (usually 1:1), stir slowly to avoid trapping air, and pour it into the printed shell around the master in a thin stream from height so bubbles fall out. Cure per spec, then peel the shell and master away. You now have a flexible multi-cavity caster that holds every cavity. For the full silicone workflow - release agents, bubble control, food-safe picks - see the silicone mold guide.
Fill, set and release
Drop the silicone caster into the rigid tray for support, then fill each cavity with your medium: filtered water to freeze, melted chocolate or candy melts, gummy mix, wax for melts, or resin/plaster for embeds. Let it set or freeze fully. Then flex the silicone outward at one corner of each cavity and the piece pops out - no twisting, no knife. Wash and reuse.
One tray, many casts
- Ice: use filtered, twice-boiled water and freeze top-down for clear cubes or spheres. For the deep dive on the silicone-ice angle, see the silicone ice cube guide.
- Chocolate & candy melts: a polished cavity gives a glossy finish; tap the filled caster to settle and release bubbles before it sets.
- Gummies: the flexible caster makes detailed gummy shapes release cleanly; a light food-safe release helps sticky mixes.
- Wax melts & tea lights: the most forgiving cast - pour warm wax, let it set, flex out. Food-safety is optional here.
- Resin & plaster embeds: small batch embeds, inclusions and trinkets come out a dozen at a time.
A note on food safety
The printed PLA/PETG tray and shell are formers - they don't need to be food-safe because they don't touch what you eat. The flexible silicone caster does, so for ice, chocolate and gummies use a food-safe platinum-cure silicone and wash the new caster before first use. For non-food casts (wax melts, display resin) you can cast or even print more freely. The food-safe molds guide covers certifications, materials and what's actually safe for direct food contact.
Print & release tips
- Match the cavity to the use. Polished for chocolate shine, smooth for clear ice, anything goes for wax.
- Keep the silicone walls right. Too thin and the caster slumps in the freezer; too thick and it won't flex to release.
- Support the caster in the tray. The rigid tray keeps the grid square so cavities don't distort while filling or freezing.
- Fill from one corner. For multi-cavity pours, let the medium flow across the grid rather than dosing each cavity, to avoid trapped air between them.
- Discard the first food batch. Freeze and toss the first batch of ice to flush any residual mold release before you use it for real.
Troubleshooting
Cubes won't release from the caster
Flex the silicone outward at a corner rather than pushing from the back. For sticky mediums (gummies, some chocolate) wipe the thinnest film of food-safe release into the cavity first. If ice sticks, run warm water over the outside of the silicone for a few seconds, then flex.
The tray won't fit my freezer drawer
Generate fewer cavities or a smaller cavity size so the overall tray is shorter, then preview it against your drawer dimensions. The tool sizes the whole grid to your cavity count, so drop a row or column and re-export.
Chocolate comes out dull instead of glossy
Dull chocolate is usually a rough cavity or untempered chocolate. Print the caster's master at a finer layer height (or polish it) so the silicone copies a smooth surface, and temper the chocolate before pouring.
The silicone caster won't cure (stays sticky)
Cure inhibition - sulphur in clay or filament, latex gloves, tin-cured tools, or release that didn't flash off. Use nitrile gloves, PLA/PETG masters, platinum-cure silicone, and let release dry fully before pouring.
Air bubbles on the surface of my casts
Pour thinner and from higher up so air falls out, and tap the filled caster a few times to release trapped bubbles. For chocolate and resin, a gentle vibration after filling settles the surface.
Cavities aren't all the same size after freezing
The flexible caster distorted because it wasn't supported. Always sit the silicone caster inside the rigid printed tray before filling and freezing so the grid stays square.
Tray mold or single silicone mold?
A multi-cavity tray is right when you want a batch of identical pieces - a tray of ice, a sheet of chocolates, a dozen gummies. If you only need one large or highly detailed piece (a single whisky sphere, a big display cast), a standalone silicone mold is simpler. For the silicone-ice angle specifically, see the silicone ice cube guide, and the silicone mold guide for the general silicone-casting workflow.