3D printing or injection moulding? Where the crossover falls

This question usually arrives late, after a business has already decided to make something and is choosing how. It is worth asking early, because the answer changes the design as well as the invoice.

We print. We will still tell you when moulding is the better buy, because a customer who should have moulded and did not is unhappy at the second reorder, and that is worse for us than the job we turned down.

What actually separates the two?

One number: the cost of the tool.

Injection moulding requires a steel or aluminium mould machined for your specific part. That mould is expensive and it is paid for before a single usable item exists. After that, each part is fast and very cheap — the marginal cost is essentially material and a few seconds of machine time.

3D printing has no tool at all. There is nothing to pay for up front, and every part costs roughly the same as the one before it. The hundredth is about the price of the first.

So the two have opposite shapes. Moulding starts high and flattens. Printing starts at nothing and stays linear. They cross somewhere, and where they cross is the whole decision.

Where does the crossover fall?

It depends on part size and complexity, but the shape of the answer is consistent:

• One to a few dozen — printing wins decisively. Tooling cost has nowhere to amortise
• Into the hundreds — it gets closer, and depends heavily on the part. A small simple part tips toward moulding sooner than a large or awkward one
• Thousands and up — moulding wins, and by a widening margin

Anyone quoting you an exact universal number is guessing. The honest version is that it is a calculation on your specific part, and it is not a hard one: tooling cost divided by the per-unit saving gives the break-even quantity.

Is cost the only consideration?

No, and this is where the decision is more interesting than the arithmetic.

Time to first part. A mould takes weeks to make. A printed part exists this week. If you are chasing a season, an event or a launch, printing can be the only option that meets the date regardless of unit cost.

Cost of changing your mind. A design change after tooling means a new tool or expensive modification. A design change in printing means editing a file. If the design is not settled, moulding is a commitment you may not be ready to make.

Geometry. Moulding constrains shape — draft angles so the part releases, uniform wall thickness, no fully enclosed internal voids. Printing does not care. Complex internal structure, lattices and shapes that could not be pulled from a mould are all straightforward. For some parts this is decisive on its own.

Volume certainty. This is the one that catches people. Moulding is cheaper per unit only if you actually sell them. Tooling for ten thousand and selling six hundred is worse than printing six hundred — and printing them tells you whether ten thousand was ever realistic.

Are the parts the same?

Not quite, and it is worth knowing where they differ.

A moulded part is homogeneous, has a uniform surface finish, and is consistent piece to piece. A printed part is built in layers, which means directional strength and visible layer lines unless finished.

For most applications neither difference matters. Where it does: a printed part is weaker across the layers than along them, so a part under a specific sustained load needs orienting deliberately or designing with that in mind. We do both, but it is a design input rather than an afterthought.

When would you tell us to mould?

Plainly: when the numbers say so.

If you need thousands of identical items, the design is settled, the geometry is mould-friendly and the deadline allows for tooling, moulding is the right answer and we will say so. We would rather be the supplier who told you that than the one who quietly took the order.

Where we are genuinely the better choice: low and mid volumes, anything still changing, anything where the pieces differ from each other, anything needed soon, and anything whose shape a mould could not release. That covers most of what a business in Malta actually needs made, which is why the business exists.

What do you need to work this out?

• What the part is and what it does
• Quantity now, and realistic quantity over a year
• Whether the design is final
• The deadline
• Any load, heat or regulatory requirement it has to meet

From that we can tell you which side of the line you are on, and if it is close we will show you the arithmetic rather than assert the answer. More on what drives printed cost specifically in what custom 3D printing costs in Malta.