Work out the cost, then apply a margin. For a 100 g PLA part on an 8-hour print, the cost is $5.15 and a 50% gross margin prices it at $10.30.
That is the mechanical half. The half that decides whether the business works is what you put into the cost.
Margin and markup are not the same number
A 50% margin on the sale price is a 100% markup on cost. A 60% margin is a 150% markup — $12.88 for the same part.
Pricing is easier to reason about as margin, because margin is the fraction of the sale price you keep. Markup is the fraction you add. Confusing them is how a shop that believes it is keeping forty percent of every sale discovers it is keeping just under thirty.
Labour is almost always the missing term
The $5.15 above has no human in it. Add twenty hands-on minutes at $25 an hour — slicing, plate prep, removal, support cleanup, packing — and the cost becomes $13.49, of which $8.33 is your time.
On a small part, labour is routinely the largest term on the invoice. On any part, it is the term that decides whether you want the order.
Two rules that follow from that:
- A minimum charge is not greed. Under about half an hour of hands-on work, the setup dominates and per-gram pricing loses money on every job.
- Batch identical parts. Ten copies on one plate share the slicing and the plate prep, so the labour per part collapses while the plastic per part does not move.
What a market will bear is a separate question
Cost tells you the floor. It does not tell you the ceiling, and pricing purely on cost leaves money on the table for anything where the value is in the design, the fit or the turnaround rather than the grams.
The one thing cost-plus does guarantee is that you will not accidentally sell below the floor, which is the failure mode that actually closes print businesses.
Model your own margin, labour rate and failure allowance in the print cost calculator, or read the longer treatment in the resale pricing guide.