A soap loaf mould that stopped bulging
Silicone inner, rigid sleeve, brand relief on the base.
Read the recordProject record · Homeware · Cast silicone for concrete
A concrete planter mould that cast a drainage hole and three base feet in a single pour.
A homewares brand was pouring concrete planters, then drilling drainage holes and gluing on rubber feet by hand. They wanted a mould that put both features into the casting itself, and they wanted the wall thickness controlled so the finished planter did not fracture in transit.
The brief
A finished planter, out of one mould, one pour.
The brand had a planter range that sold well, but every finished piece went through three post-cast steps: drilling a drainage hole in the base, sanding the drill marks, and gluing on three rubber feet. Each step added time, added cost, and added a failure mode.
They wanted a mould that put the drainage hole into the casting itself, cast three low feet into the base, and gave a uniform wall thickness so the planter did not fracture along a thin spot in transit.
The finish had to be smooth on the outside. Concrete casting silicone is very good at capturing texture. It is equally good at capturing bench dust. So the outer face of the mould had to release from a master that had been polished, not just smoothed.
The problem
A hole, three feet and a controlled wall — from one mould.
The drainage hole is an internal feature. To cast a hole into a concrete planter, the mould has to include a plug that stays in place during the pour and lifts out afterwards. A silicone plug flexes for release; a rigid plug jams. The plug had to be silicone with a rigid stem.
The base feet are the opposite problem. They are external features that sit on the underside of the base. The mould has to have three matching recesses in what becomes the top surface during pouring. Those recesses have to release cleanly around a full-strength concrete cure, which likes to bond to itself around any positive shape.
The wall thickness is really a levelling problem, not a mould problem. If the mould sits off-level during pour, the concrete pools to the low side and the wall thickens on that side and thins on the other. So the mould had to include its own levelling base, and the pouring process had to be documented.
Plug for the hole, base for the feet, shell for the wall.
Illustrative schematic. Real tools include additional detail (runners, vents, ejector positions).
What we did
Plug for the hole, recesses for the feet, level base for the wall.
Every feature the finished planter needed was designed into the mould, not added after.
CAD the planter with all three features integrated
The planter was modelled with the drainage hole, three base-foot recesses, and a uniform 8 mm wall. The mould was designed backwards from that geometry, not the other way around.
CNC the master in rigid tooling foam
The master was CNC-cut in a high-density tooling foam, then hand-polished. Polishing the master pays back in the finished planter surface — the mould captures the polish, the concrete captures the mould.
Cast the outer silicone shell
Concrete-grade silicone was cast over the master to form the outer shell. Wall thickness was set at 15 mm to resist the hydrostatic load of the concrete pour.
Fabricate the drainage plug
The drainage plug was cast in silicone with a rigid aluminium stem. The stem lets the plug be pulled cleanly out of the cured concrete; the silicone lets the concrete release from the plug without cracking around the hole.
Build the levelling base
A levelling base was CNC-cut in phenolic, with the three foot-recess positives mounted on it. The mould sits on the base during pour, and the base carries the recesses for the feet.
Trial pour with the brand's own mix
First-off planters were poured with the brand's own concrete mix. The plug came out clean, the base feet released without cracking, the wall was uniform to within half a millimetre. Signed off on the third pour.
The stages
A typical run, drawn out on a timeline.
Drag the timeline left and right, or use the arrow keys. Each stage explains what happens and roughly how long it takes.
Drag · tap a stage for detail
Total working time on a job of this shape: about 4 weeks (28 working days). Lead times shift with drawing changes, sign-off pace and material availability.
The commercial bit
The numbers, out in the open.
Rather than quote a figure that would only be right for one job, here is a worked example based on a realistic project of this shape. Your quote follows the same shape, with your part, your volume and your material.
Worked example
A homewares brand casting 25 planters a week over a two-year retail cycle.
| Master pattern + CAD | £1,850 one-off |
|---|---|
| Silicone outer shell | £850 one-off |
| Drainage plug + levelling base | £620 one-off |
| Tool amortised over 2,600 planters | ≈ £1.28 per planter |
| Concrete, colouring, cure | your existing cost |
Numbers are indicative for a 240 mm × 180 mm planter with a single drainage hole and three cast base feet. Additional plug positions push tooling up moderately.
Where the job ended up.
One pour, one planter, no drill, no glue. It changed the unit economics on the whole range.
Founder, homewares brand
Where it landed
The finished piece, in context.
Every project record on this site is a real piece of work delivered to a real client, with the tooling and the numbers to back it up. This one is no exception.
If you have a similar problem, please send a drawing or a photograph. We will come back with a route, a lead time, and an indicative cost.
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Other work of this kind.
A pillar candle mould with hinged sleeve
Tapered wall silicone tool that released clean every pour.
Read the recordNext step
Casting concrete into anything that needs post-processing?
Send us the finished piece — a photograph or a drawing — and describe what you're doing after the cast. Drilling, sanding, gluing feet, spraying a base — each of those is usually solvable inside the mould, in one pour.
If you're currently pouring into plaster, timber or wire-formed cardboard, silicone typically pays back inside 200 to 400 castings, depending on the finish tolerance you need. We'll model that for your specific volumes if you send them.
Ready to start?
Tell us what you need to make, and we'll explain how to mould it.
Send us a drawing, photograph or sample, and we'll come back with a route, a material recommendation and a price.
Real people, a real workshop
You deal with the people who make it.
No call centre and no middlemen. When you contact TCI Mouldings, you speak to the team who design, build and check your mould.
- A real Warwickshire workshopUnit 15, Waterloo Park, Bidford-on-Avon, Alcester B50 4JG.
- Real people on the phoneCall the team on 01789 224228, Monday to Friday.
- The same team on every jobDesign, production and aftercare come from the people you see here.
- Part of TCI GroupFive specialist brands, one engineering team. Visit TCI Group.
Thomas LaneManaging Director
George PrestonDesign & Project Manager
Kelly BallingerHead of Partnerships
Jim AndertonProduction Manager
TheodoreEmployee Welfare