Bottle Drawing Checklist: 14 Points Before a Mould Is Cut
By Joe Joo · 8PCK · Shantou · Updated 26 October 2026
Most mould quotes stall on the same thing: the drawing is a shape, not a specification. Here are the fourteen items a factory needs before it can cut steel — and what happens when each is missing.
A drawing that only shows the silhouette will get you a price and a delay. The silhouette is the easy part; what decides the tool, the tolerance and the scrap rate sits in details that are usually left off.
This is the checklist we actually run before quoting a mould. Fourteen items, grouped in four blocks. If a brief arrives with eight of them, we can start the DFM note; with fourteen, we can quote the tool.
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Block 1 · Geometry: Five Numbers That Define the Tool
1. Nominal capacity — and whether it means brimful or filled to the neck. A 200 ml brimful bottle is about 185 ml filled; a mould cut for the wrong reading comes out 8 % small.
2. Neck finish — written as a standard, e.g. 24/410, not as 'screw cap'. The T-dimension and thread pitch decide which pumps exist; a non-standard neck means a custom closure as well as a custom bottle.
3. Overall height, measured from the base to the top of the neck thread, with the closure excluded. This is not the same as the packed height, and mixing the two is how a carton ends up 10 mm short.
4. Maximum diameter, at the widest point — usually the shoulder, not the body. It sets the cavity pitch in the mould and the carton's internal dimension.
5. Base geometry — flat, concave, or with a push-up. A concave base adds stiffness but costs a deeper draw; on a thin wall it is often the difference between standing straight and wobbling.
Block 2 · Wall and Weight: the Number That Decides the Price
6. Target gram weight is more useful than wall thickness, because weight is what the factory buys and what the price follows. Give the weight and the wall range that produces it.
7. Wall at the shoulder — the thinnest point on most blow-moulded bottles and the first to flex. Under 0.55 mm a pump stroke will deform it and the pump will draw air.
8. Wall at the base — where impact lands. A base at the same thickness as the body will crack before it dents on a drop test.
9. Weight tolerance, typically ±5 % on a blow-moulded part and ±2 % on injection. Without a stated tolerance, a 21 g bottle against a 22 g spec is neither right nor wrong.
Block 3 · Closure: the Part Buyers Forget
10. Thread standard and length — 24/410 with a 12 mm skirt is a different tool from 24/410 with a 9 mm skirt, even though buyers call both '24/410'.
11. Seal type — plug seal, land seal, or an induction liner. Each needs a different rim geometry at the neck, and the rim is cut into the tool.
12. Application torque — how hard the capping machine turns the closure. A 2.5 N·m pump on a 0.5 mm shoulder is a warranty claim waiting to happen.
Block 4 · Material, Colour and What Happens After Moulding
13. Resin grade and colour — virgin, rPET percentage, masterbatch reference. A clear bottle asked to run 30 % rPET will not match a virgin sample; that is a colour decision taken before the tool, not after.
14. Decoration and packing — screen, label, spray, metallising, and how the part ships. Decoration affects the MOQ and the handling; packing affects the carton that must survive the shoulder.
What Happens When an Item Is Missing
Missing capacity convention: the mould comes out the wrong size. This is the most expensive error in the list because it is discovered at T1, after steel is cut.
Missing neck standard: the quote cannot include a closure, and the buyer discovers the pump does not fit when the sample arrives.
Missing weight: the factory guesses, quotes low, and the real part comes out heavier and more expensive — or lighter and too flexible.
Missing decoration: the MOQ is quoted at 1,000 and turns out to be 3,000 once spray is added.
Missing colour: a clear part with recycled content fails the visual comparison the buyer makes against their existing bottle.
A Drawing Is Not a CAD File
A STEP file alone is not a specification. It carries geometry and nothing else: no capacity convention, no weight, no thread standard, no seal type, no tolerance. We can read the shape from the file and the intent from the checklist — and we need both.
If you have only a photograph of a competitor's bottle, send that plus the fourteen answers you do have. The DFM note will tell you what is still unknown and what it will cost to assume.
Questions We Get on This
What must a bottle drawing include before a mould is quoted?
Fourteen items: capacity convention, neck standard, height, diameter, base shape, target weight, wall at shoulder and base, weight tolerance, thread length, seal type, torque, resin grade and colour, and decoration.
Is a STEP file enough to quote a mould?
No. A STEP file carries geometry only; capacity convention, weight, thread standard, seal type and tolerances have to be stated separately.
What is the most expensive thing to leave off a drawing?
The capacity convention. A bottle cut for brimful instead of filled-to-neck comes out about 8 % small, and it is discovered at T1 after the steel is cut.
Sizes That Fit This Guide
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Tell us the capacity, the neck and the quantity. You get unit price, lead time and a sample plan — not a catalogue.
Every batch is gauged at the neck and weighed. The documents travel with the shipment.