1. Inputs and units
Use one currency across both scenarios. Spool weight and plate material are in grams, electrical power in watts, electricity price per kWh and print duration in hours. Setup, finishing and retry handling use minutes. Delivered quantity and parts per plate are positive integers. Grams and hours describe the entire full plate, including supports and purge material.
2. Whole plates and expected attempts
plates = ceiling(delivered quantity / parts per plate)
attempts = plates / (1 − failure fraction)
failed attempts = attempts − plates
The model repeats independent full-plate attempts until the required number succeed. Failure consumes full material and time. The last plate is costed in full even when its capacity exceeds requested quantity. Extra parts get no revenue credit. Expected attempts may be fractional; they are not a schedule or a prediction for one job.
3. Direct production costs
material = attempts × plate grams × spool price / net spool grams
energy = attempts × plate hours × watts / 1,000 × tariff
depreciation = attempts × plate hours × (purchase − residual value) / lifetime hours
maintenance = attempts × plate hours × maintenance rate
Residual value cannot exceed purchase cost. Lifetime is a planning assumption supplied by the user. Depreciation is an economic allocation and not an additional cash payment. Do not count the same wear cost again under maintenance.
4. Labour and other costs
setup labour = setup minutes / 60 × labour rate
finishing labour = delivered quantity × minutes per part / 60 × labour rate
retry labour = failed attempts × retry handling minutes / 60 × labour rate
packaging = delivered quantity × packaging cost
production cost = all above costs + other order cost
Routine successful-plate handling is not a separate automatic line. Include its order total in setup for each scenario. Finishing and packaging are charged only for delivered good parts. Include design, administration, shipping or overhead explicitly if relevant and avoid counting them twice.
5. Price, payment fees and surplus
Margin method: price = (production cost + fixed fee) / (1 − payment fee fraction − target margin fraction)
Markup method: price = (production cost × (1 + markup fraction) + fixed fee) / (1 − payment fee fraction)
payment fees = price × fee fraction + fixed fee
surplus = price − payment fees − production cost
The fixed payment fee is charged once for the entire order. Percentage fees use the calculated before-tax selling price. Real processors may use a different taxable base or multiple payments. The tool does not implement those contracts. Margin plus payment-fee percentage must be below 99.99%.
6. Precision and limits
Intermediate costs use JavaScript double precision. Total quote rounds upward to the minor unit, including whole-yen rounding for JPY. Ratios and per-part values are rounded only for display. The report is not an invoice engine. Orders are limited to 100,000 delivered parts, failure rates to 95%, and computed quotes to 1 trillion selected currency units. Extreme combinations are rejected instead of returning Infinity.
7. Model boundaries
Only FDM is modeled. No tax advice, VAT calculation, strength assurance, geometry analysis, STL/G-code parsing, resin workflow, returns or demand forecast is provided. Early failures, part-level defects, correlated failures, varying last plates and real production scheduling require a more detailed model. Neither route should be accepted solely because its cost is lower.
Sources and independent context
This implementation is original. The Prusa cost guide and 3D Printing Stack Exchange discussion provide external context for costs beyond filament. They do not certify this tool or its model.