Multiplying model milliliters by bottle price produces a material estimate, not the cost of a finished resin part. Supports and rafts consume resin; liquid remains on tools and in cleaning losses; washing, drying, curing, removal, inspection, and safe disposal all require resources. The useful denominator is the number of accepted, fully processed parts.
1. Start with total sliced volume, not model volume alone
Use the slicer's total resin estimate including model, supports, raft, and any additional structures. Divide bottle price by bottle volume to obtain cost per mL, then multiply by the total. Keep the profile and orientation with the record because support strategy can change consumption substantially.
The slicer cannot see every loss: resin retained on the platform, tools, gloves, filters, failed exposure tests, vat cleaning, spills, and material retired after contamination. Compare purchased volume with the volume assigned to accepted work over a stable period to create a workshop-specific loss factor instead of guessing forever.
2. Allocate solvent by useful processing capacity
IPA or a validated washing solution can process multiple jobs before replacement, so charging a whole container to one print is wrong. Track purchase and disposal cost, replenishment, pre-rinse usage, and the number or total volume of accepted parts washed before the bath is replaced. A two-stage wash may use more containers but extend the life of the cleaner final bath.
Follow the material and equipment manufacturer's wash limits. Formlabs notes that geometry, contamination, and solvent condition affect washing, and that over-washing some materials can be harmful. Cost reduction must not override the specified workflow or local safety and disposal rules.
3. Measure direct labor separately from unattended wash and cure time
Direct labor includes platform removal, handling, support removal, transferring between stages, surface cleanup, inspection, and packaging. Machine cycle time includes automated washing, drying where equipment is occupied, and curing. A worker may do other tasks while a station runs, so elapsed post-processing time should not automatically become labor time.
Time several representative batches and divide direct minutes by accepted quantity. Small delicate parts can require more touch labor than large simple parts. If supports are removed before or after curing depending on material and quality requirements, maintain separate workflow records rather than forcing one average onto every product.
4. Include PPE and disposal without diluting safety requirements
Gloves, filters, wipes, release tools, replacement film, mixing containers, and spill-control supplies are production inputs. Record recurring purchases by month or batch and allocate them through a consistent driver. Durable wash and cure equipment can use an hourly or per-cycle reserve similar to the printer.
Always follow the resin and solvent safety data sheets and local waste rules. Never pour uncured resin or contaminated washing solution into drains. The cost model should make compliant handling affordable; it must not recommend unsafe shortcuts to reach a target price.
- Use the current SDS and manufacturer processing instructions.
- Track gloves, filters, wipes, film, and cleaning tools.
- Include compliant waste collection and disposal cost.
- Keep ventilation and safety equipment in facility overhead or the process rate.
5. Apply failure to the full direct process cost
A failed resin part loses more than liquid. Exposure time, platform capacity, preparation, solvent condition, PPE, removal, and inspection may all be consumed. Calculate the total direct cost of the build, then divide by accepted output. Classify failures by support, adhesion, exposure, orientation, contamination, and post-processing so prevention work targets the real cause.
Use recent comparable jobs rather than one workshop-wide percentage. A small validated miniature and a new large hollow enclosure do not share the same risk. Separate development tests from production failures when customers pay a design or validation fee.
6. Add fees, overhead, and profit only after the process cost is visible
Combine resin, loss, printer and station reserves, energy, consumables, direct labor, compliant disposal, packaging, and accepted-yield adjustment. That total is the internal cost floor. Add marketplace or payment fees, design value, business overhead, tax treatment, and target profit according to the sales channel.
If the resulting market price is too high, compare orientation, support strategy, hollowing where technically suitable, batch layout, wash workflow, and labor fixtures. Lowering the selling price without changing the process only hides the loss. Preserve the before-and-after record so a cheaper workflow is also demonstrably acceptable.
References and further reading
These manufacturer and technical references support the workflow described above. Use them as a starting point, then validate costs and settings in your own workshop.
Test your numbers