FDM printing or injection moulding for small batches: differences and break-even

For a small batch of tens to hundreds of pieces, FDM 3D printing is usually cheaper and faster because it needs no mould. Injection moulding needs a mould costing thousands of euros and normally 6 to 10 weeks, but at high volumes it delivers a cheaper, stronger part. In our illustrative examples, break-even lands at roughly 1,000 to 11,000 pieces.

The difference at a glance: FDM and injection moulding side by side

The figures for moulds and lead times come from the Formlabs and Hubs guides; dollar conversions are approximate (ECB rate of 30 September 2026).

Injection moulding clearly wins on unit price at high volume, surface finish, uniform strength and range of materials. FDM wins on time, on needing no tooling, and on a design change being just a change of model.

How the price arises: grams versus the mould

Printing charges for weight and time. Our indicative rates are €0.16 per gram for parts up to 50 g, €0.12 from 50 to 250 g, €0.09 above 250 g and below €0.07 for a series (price list). The unit price therefore grows with weight and falls only slowly with quantity.

With moulding you pay for the mould once, then for the cycle, typically 15 to 60 seconds (Hubs), and cheap granulate: according to Xometry, ABS comes to roughly €2.5 per kilogram. The mould is spread across the quantity, so the unit price falls as volume rises.

In the formula, use the weight of the printed part at the chosen infill (5 to 100%), not the weight of the moulded part. A moulded part is solid, so it tends to be heavier.

Break-even point: the calculation and three illustrative examples

The formula is the one from our comparison of four technologies; the only difference is that you do not need to guess the printed unit price, you calculate it from weight:

Break-even = mould cost ÷ (FDM unit price - moulded unit price), where FDM unit price = weight in grams × rate per gram.

All three are illustrative examples, not a quotation. The mould and unit price in column A come from a real Formlabs example (two-cavity mould; ECB rate of 30 September 2026), and the 8 g weight is our assumption. Columns B and C are based on a Slovak quotation from 2024 for ABS parts, with the unit price quoted at 10,000 pieces. The sources do not state VAT; our prices are final (we are not a VAT payer). The series rate in the table is exactly €0.07/g, and at a lower rate the break-even comes out higher still.

Three things follow from the examples:

1. The break-even depends mainly on part weight. A printed unit costs more with every gram, a moulded one hardly changes. A heavier part therefore breaks even at around a thousand pieces, a lighter one in the thousands. That A comes out similar to B is down to its cheaper two-cavity mould: the second key input is the mould price.
2. The real break-even is somewhat lower. In a smaller run the moulded unit is dearer, and the moulder may charge a set-up fee for each production run (Protolabs). Mould shipping and trial samples are not included in the examples.
3. At our quantities printing wins clearly. For 100 pieces of part B, printing comes to €560 (at most €245 in a series) and moulding to €16,864 (mould plus 100 × €0.64). For 500 pieces it is €2,800 (at most €1,225 in a series) against €17,120.

We cannot promise thousands of pieces: typically it is tens to hundreds. The quantity from which the rate below €0.07/g applies is set in the quote.

Time and capacity: the second criterion after price

A printed part is ready in days, a standard order usually in 2 to 5 working days. Moulding starts with the mould: according to Hubs, 4 to 6 weeks for the mould and 2 to 4 weeks to produce the parts.

At large quantities it reverses. The same Slovak page from 2024 calculates that 4,373 pieces of a 35 g part would take about 31 days on a farm of ten printers, while moulding would manage it in 2.5 days. We do not offer that capacity, so at larger quantities lead time matters as well as price.

Strength, surface and dimensions

A moulded part is a single body. An FDM part is built from layers and, according to Prusa, is stronger in one direction than in another. For PETG, Prusa Polymers states a tensile yield strength of printed specimens of 47 MPa horizontally and 50 MPa vertically, but a notched impact strength of only 3 kJ/m² vertically against 6 kJ/m² horizontally (100% infill, 0.2 mm layer). An older study from 2002 (Ahn et al.) measured 65 to 72% of the tensile strength of moulded ABS for ABS printed on an industrial machine; today's machines and materials differ. We therefore choose part orientation by the direction of the load, and the article on materials for end-use parts goes further into materials.

The surface of a moulded part copies the mould: from a fine texture to a polished surface with roughness Ra below 0.10 µm, without finishing. Marks remain from the parting line, ejector pins and gate (Hubs). An FDM part has visible layers, and a smoother surface comes only with finishing. According to Hubs, moulded parts are practically identical, whereas prints of the same part differ slightly. Allow for clearance in an assembly.

Design and materials

Moulding imposes rules on shape: a draft of at least 2° on vertical walls, uniform wall thickness, ribs half the wall thickness and no undercuts, which need side cores and make the mould dearer. For runs under 1,000 pieces, Hubs notes it is often cheaper to add a feature afterwards, for example by drilling. FDM needs no draft, but an overhang beyond roughly 45° usually needs supports, and a wall should have at least two perimeters, around 0.9 mm with a 0.4 mm nozzle (Prusa).

A part designed for moulding can almost always be printed; the reverse is not true. If you plan a mould later, follow these rules at the prototype stage. 3D modelling handles the redesign, and this article explains when to hand modelling to a specialist.

Moulding can process more than 100 plastics and elastomers (Protolabs). We print PLA, PETG, ASA, nylon and TPU, and on request PC Blend and filled materials. If you need polypropylene, a glass-filled or flame-retardant plastic or a certified material, the part belongs to moulding with a supplier who can document it. Parts from our printing are not, without a separate written agreement, intended for uses where failure could endanger life, health or property.

When to move from printing to injection moulding

Moulding pays off when most of these signals apply:

• the design is frozen and no changes are expected,
• demand is stably above the break-even from your calculation (Hubs recommends moulding from roughly 500 pieces),
• FDM falls short on properties: material, surface or uniform strength,
• thousands of pieces would mean weeks of printing,
• the unit price at high volume drops below what printing can reach.

A sequence that works:

1. FDM prototypes, designed to moulding rules from the start (3D-printed prototypes).
2. A pilot run of 20 to 200 pieces from FDM, used in real conditions before the mould is ordered (small-batch production).
3. The calculation and two to three quotations. Ask for the mould price and unit price at 500, 1,000 and 5,000 pieces, the number of cavities, the mould material and guaranteed number of shots, the set-up fee for each run, who owns the mould, the lead time for samples and shipping. Some moulders do not publish mould prices or minimum quantities, so ask directly.
4. An aluminium mould for 500 to 10,000 pieces is, according to Formlabs, a cheaper and faster route than steel, which is ideal from 5,000 pieces.
5. Printing stays for spares, variants and as a bridge: according to Formlabs, a short run can be made before the tooling is finished.

How we quote it

For custom FDM printing we need the model, the quantity, the material and the place where the part is loaded. Which documents help is described in the article on quote documents. We usually send a quote within 24 hours on working days, and the printability check is free. If a mould pays off better, we say so in the quote. Send us the quantity and the part, and we will work it out together.