What does a plastic box supplier set price include?

Answer: Body, lid and hardware, normally without insert, printing or carton. Confirm all four first.

Why is the MOQ a multiple of twelve?

Answer: Six lid cavities against four base cavities pair only on a common multiple. Four and four drops it to multiples of four.

Can we use an existing shared mould?

Answer: Yes, after measuring three samples and confirming cavity wear is in tolerance, with rework costs in writing.

How much longer does a mixed order take?

Answer: Five to seven days: three for printing, 2.5 hours per changeover, a shift for assembly.

Do we sample sets or pieces?

Answer: Boxes by set, cases by piece. Name the unit and judgement sheet in the contract.

Plastic box supplier: four reasons one quote looks 1.8x cheaper

Quick answer: A box quote and a case quote are not comparable. A plastic box supplier prices a box per set, lid included, and a case per piece, so mould count, cavity pairing and MOQ all differ. Align the units and most of a 1.8x gap disappears.

Why comparing unit price fails
Two moulds, two trials
Quoted per set or per piece
MOQ rounds to the pair
Mixed orders: three lost stages
Sampling by set or by piece
FAQ

1. Why comparing unit price fails

One factory can supply both and write two quotes: a box per set, a case per piece. The columns cannot be compared.

Item	Box	Case
Unit	Per set, lid included	Per piece, complete
Moulds	Lid tool plus base tool	One or two
Part weight	0.38 kg per set	2.6 kg per piece
MOQ basis	Paired sets	Pieces
Sampling	Set	Piece
Driven by	Printing, assembly	Moulding, finishing

A plastic box supplier earns on assembly and printing; a case earns on mould amortisation. Once you see that, a cheap box that ends up dear stops being a surprise.

2. Two moulds, two trials

Lid and base differ in wall and shrinkage, so one tool producing both fights itself at the mating face. A plastic box supplier that quotes a single tool is quoting a compromise. The route is two tools, two trials, then the pair checked as a set.

Plastic box supplier: closed grey case with a combination lock between two latches, folding handle, plain studio background

Two tools means two charges: 19,000 yuan for the lid, 23,000 for the base, 42,000 together. A single line reading 42,000 is honest; a line reading 20,000 invites the question where the second tool is. The lid tool trials first for flatness, the base second for spigot depth.

Shared tooling is the other trap. When a plastic box supplier says the mould exists and there is no fee, it has usually run for someone else, with worn cavities and their dimensions. Measure three samples first.

3. Quoted per set or per piece

The same box at 2.1 and at 3.8 yuan usually differs in scope, not greed.

Basis	Wording	To match, add
Body only	2.1 yuan per piece	Lid, 1.3 yuan more
Lid, no insert	3.4 yuan per set	Insert, 0.4 yuan
One colour print	3.6 yuan per set	Second colour, 0.25 yuan
Packed	3.8 yuan per set	Carton and pallet

The 1.8x sits between rows one and four. Add lid, insert, printing and packing and both suppliers land between 3.5 and 3.9 yuan, a gap under ten percent.

So the first move is a four-line sheet any plastic box supplier can fill in a day.

4. MOQ rounds to the pair

A box MOQ is not chosen by sales; it is the common multiple of the two cavity counts. A plastic box supplier running six lid cavities against four base cavities must ship sets in twelves.

Plastic box supplier: grey case corner with a black latch and parting line, racks of cases behind

Cavities	Smallest run	Changeover	Shots for 900 sets
Lid 6, base 4	12 sets	2.5 hours	Base 225, lid 150
Lid 4, base 4	4 sets	2 hours	225 each
Lid 8, base 6	24 sets	3 hours	Base 150, lid 113

Nine hundred sets is a common first order: the base tool runs 225 shots, one shift, while the lid tool runs 150 and the spare capacity absorbs rejects. Below that, changeover adds 0.6 yuan per set.

Three hundred sets works with natural resin, no colour change, no printing.

5. Mixed orders: three lost stages

An order holding both boxes and cases adds three stages that rarely reach the schedule. A plastic box supplier new to mixed orders discovers them late.

Printing: three days for one colour, four for two; cases are unprinted and get merged away.
Changeover: 2.5 hours for a box tool, four for a case tool with lifting, so two switches eat a shift.
Assembly: inserts and lids are hand-fitted at 240 sets per shift; cases come off the tool complete.

Printing gets squeezed first. To keep the date attractive a supplier pushes print into the last two days, and one colour rejection blocks the batch at the door.

Mixed pallets waste about a tenth of the container.

6. Sampling by set or by piece

Boxes are sampled by set, cases by piece; getting this wrong doubles the count. Fifty sets is a hundred parts, fifty cases is fifty.

For a box, inspection sits at the mating face: gap within 0.5 mm, no corner lift when closed, latches firm after 5,000 cycles. For a case it sits on the whole: three-high stacking for 24 hours, corners intact after a drop. The two need different judgement, feeler gauges for boxes, instruments for cases. Run the gauge into all four corners, because one corner hides a warp. Stack one layer above the real storage height, since the bottom unit carries more. Drop corners, then edges, then faces. Put it in a judgement sheet and nobody argues at the table.

A plastic box supplier that asks what a sampling unit is has not run mixed orders.

Conclusion

Most gaps between plastic box supplier quotes are baseline problems, not price problems: sets against pieces, two tools against one, paired MOQs against round numbers. Align them and a 1.8x spread narrows to under ten percent. Do that first and a plastic box supplier becomes comparable.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.