Silicone moulds for plaster crafts, figurines and vases
Plaster sets by chemical reaction, not by cooling. It warms, it swells, and it is abrasive to pull, so a mould that works for resin usually fails here. These are cut for the pieces craft makers actually sell: small figures, bud vases, candle vessels, trinket trays and planters.
- Heavier walls than a resin mould
- A release lip on every cavity
- Large and deep formats, not just 8 cm shapes
- Sample in 7 days from drawing sign-off
Six things craft makers cast most
The object decides the cavity. A tray is a release problem, a vase is an air problem, a candle vessel is a core problem. We cut each one to the failure that object actually has.
Vases and bud vases
A vase fails at the neck, not the body. The narrowest section is the last to fill and the first place air gets trapped, so the cast tears or comes out short.
We cut the neck as a separate insert, or open the cavity from the base, so the piece pulls without a vacuum pocket forming behind it.
Candle vessels and jars
The outer wall is easy. The inner cavity is the mould: it has to pull clean at the rim and leave a wall thin enough to hold heat and a wick without cracking.
Lids are cut as a matched pair on the same master, so the register is a measured fit rather than a guess across two moulds.
Trinket trays and dishes
Rim thickness decides whether the piece survives handling. At 3 mm the rim chips on the way out of the mould; at 5 mm it survives a market stall and a dishwasher-free wash.
Wavy, petal and scalloped edges are cut with a rounded lip so the plaster releases from the edge inward instead of tearing along the pattern.
Planters and pots
A tall pot with wet plaster in it pushes its own walls outward. Larger sizes are cut over a rigid shell so the sides stay straight and the base stays flat instead of doming.
Drainage holes are formed by the mould, not drilled afterwards, which keeps the rim clean and removes a second operation.
Figurines and small ornaments
Ears, tails, wings and fingers are undercuts. Cut them in one piece and they snap on demould; leave them to the cast and they never come out.
We split the cavity around those features and put a release lip at the parting line, so a small part comes out whole rather than half-pulled.
Embossed and relief pieces
Lace, ribbing, floral relief and Nordic line work all read as depth. The detail has to be cut deep enough to survive a coat of paint, and shallow enough that the plaster fills it before it starts to set.
We test the relief on a sample cast before the production mould is cut.
Plaster is not resin with a different colour
Three things change when you pour plaster instead of resin, and each one moves a different part of the mould.
It expands while it sets
Plaster of Paris warms and swells during cure, then shrinks back as it dries. The cavity is cut with that movement in mind, so the finished cast is the size on the drawing, not the size of the mould.
It is abrasive
Gypsum slurry wears a thin silicone wall from the inside, pull after pull. Walls are cut heavier than a resin mould so the cavity still releases cleanly at cast two hundred.
It is heavy
A filled plaster mould pulls itself open. Anything above a small ornament is cut over a rigid jacket so the cavity does not bulge under the weight of the mix.
Most craft moulds stop at 8 cm. That is a supply problem, not a design problem.
The most common complaint in plaster casting groups is not price or detail. It is size: the moulds available are small, shallow, or both, and nobody sells a 25 cm vase. A large mould is not the same mould scaled up.
- Wall thickness scales with the part, not with the detail. A 25 cm vase holds several kilos of wet plaster; the wall has to carry that load without stretching at the base.
- Deep cavities need a vent or a split. Past roughly 12 cm of draw, a single-piece cavity traps air and the cast comes out with voids under the surface.
- Big pieces need a jacket. Trays, wide bowls and tall pots are cut over a fibreglass or printed shell so the sides stay flat while the plaster sets.
- Weight limits the pull. Above a few kilos per cast, the mould is lifted off the piece rather than the piece out of the mould, and the geometry has to allow that.
Tell us the finished size and the deepest section and we will tell you whether that shape is a one-piece mould or needs a jacket. We quote the mould, not the closest shape we already have.
One cavity, four materials
Many of these shapes sell into more than one craft, and one mould can often serve two of them. It cannot serve all four by default, because each material loads the wall differently.
| Material | What it does to the mould | What we change |
|---|---|---|
| Plaster of Paris, gypsum | Warms and expands on set, abrasive to pull | Heavier wall, release lip, shrink allowance in the cavity |
| Cement, Jesmonite | Heavy, exothermic, can leave a hard film | Thicker wall plus a rigid jacket on anything wide |
| Epoxy and UV resin | Cures hot, sticks to a rough surface | Lower shore hardness, polished cavity |
| Pillar and container wax | Shrinks on cooling, tears at thin detail | Softer silicone, deeper relief, wider release angle |
If you plan to sell the same shape in two materials, say so at quotation. We cut for the harder of the two, which costs less than two moulds. If you need a mould this week rather than in three, the stock silicone moulds cover the small shapes we keep ready.
If you sell a kit, the cavity is the product
Send what you have
A 3D file, a drawing, a handmade master, or a cast from a mould you already sell. We measure the cavity, correct for the shrinkage of your material, and cut a replacement that releases the same way.
No file yet? Send a photo with overall dimensions and we will tell you what the mould needs before you spend on tooling.
Built for the shelf
For DIY kit brands we cut the mould, the tray it packs into and a lid that registers, so the box, the cavity and the finished piece line up without a second supplier.
Private label and retail packaging can be quoted on the same line as the tooling, from the kit layout you already use.
- Sample in 7 days after drawing sign-off, so you can cast and paint before committing to a batch.
- Batch in 15 days after sample approval.
- Custom moulds from 500 pcs. Stock shapes ship from 5 pcs, so a small shop can test before a full range.
- Repeat orders stay identical — the master is kept, so a reorder in two years is the same cavity, not a redraw.
Four numbers and we can price the mould
| What we ask | Why it changes the price |
|---|---|
| Finished piece size | Cavity volume, wall thickness, and whether a jacket is needed |
| Deepest section | Release angle, venting, and whether the core splits |
| Pieces per casting run | Single cavity or multi-cavity mould |
| Material and expected pulls | Shore hardness and wall thickness of the silicone |
A mould for 50 casts and one for 500 are cut differently. Tell us the number you expect and the mould is sized to it.
Plaster mould questions
Can one mould cast plaster, cement and resin?
Two of the three, usually. Plaster and cement can share a mould cut for cement, because it is the heavier load. Resin in the same cavity will work but the release is less clean, and a mould cut for resin will bulge under filled cement. Tell us every material you plan to pour before we cut.
How many casts will a plaster mould last?
It depends on wall thickness, how the cast is demoulded and whether a release agent is used. A plaster mould pulled by hand with a lip typically runs into the hundreds; the same wall pulled by a fingernail or washed with a solvent will not. We size the wall to the number of pulls you tell us.
Why are most craft moulds so small?
Because a large cavity is a different mould, not a bigger one. Past about 12 cm of draw a single-piece cavity traps air, and past a few kilos of plaster it needs a rigid jacket. Both add cost, so most stock ranges stay small. We cut both, and quote them separately so you can see what the size costs.
Can you match a mould I already sell?
Yes. Send the mould or a cast from it. We measure the cavity, correct for the shrinkage of your material, and cut a replacement that releases the same way. If the original has a flaw you have been working around, tell us what it is and we will correct it rather than copy it.
Do you make mould sets for children's plaster painting kits?
Yes. Shallow cavities with rounded internal corners, a release lip on every shape, and a softer shore so a small hand can demould without snapping an ear or a leg. If the kit is sold as a toy, tell us the market, because material and labelling requirements differ between the EU, US and UK.
What file formats can you work from?
STL, STEP, IGES and 3MF are all fine. A scan of a handmade master works too. If you only have photos and dimensions, send those and we will model it and confirm the shape on a printed master before any silicone is poured.
Other ranges from the same mould shop
Send the file, get the tooling cost
A drawing, a photo with dimensions or a cast you already sell. We reply with mould cost, wall thickness and the sample date.