Part size and material volume
The obvious one. A bigger part uses more material and occupies the machine longer. But volume is not the same as bounding-box size — a hollow or lightly infilled part can be far cheaper than a solid one of identical outer dimensions.
Geometry and how it has to be printed
Geometry drives cost more than most people expect. Overhangs need support material that is later removed. Tall thin features may need slower printing. Fine detail may need a smaller layer height, which multiplies print time.
Two parts with the same volume can differ substantially in price purely because of how they have to be oriented and supported.
Material choice
Materials differ in raw cost, but also in how forgiving they are to print. A material chosen for strength, temperature resistance, or a specific finish may print slower, need more careful setup, or have a higher scrap risk.
This is why we ask what the part is for before quoting. Specifying a demanding material for a part that never needed it is a common way to pay more than necessary.
Print time and machine occupancy
Additive manufacturing prices machine hours, not just material. A part that takes eighteen hours ties up capacity that a two-hour part does not, and that is reflected in the quote.
Quantity
Quantity cuts both ways. Setup and review effort is spread across more parts, which helps. But unlike injection moulding, additive manufacturing does not collapse to near-zero marginal cost — the tenth part still takes machine time.
The practical effect: small batches get meaningfully better per-unit pricing than one-offs, and the curve then flattens.
Finishing requirements
Support removal, surface work, and any post-processing are real labour. A part that ships as-printed and a part that needs a smooth finish are different jobs even from the same file.
Why we quote after review, not before
Every one of these factors is visible only once we have looked at the actual design and understood what the part is for. That is why Helix reviews the submission first and then quotes, rather than publishing a per-gram rate that would be wrong for most projects.
It also means the quote comes with the reasoning attached, so you can see where the cost sits and whether a change to the design or material would move it.