Print-service bureau, how do you build instant STL quote (material × volume × layer height) on Magento?

Print-service bureau is a 35-50% gross-margin services line bolted onto catalog sales. Customer uploads STL / STEP / 3MF, gets an instant quote, pays, you print + ship. Three pieces:

1. File upload + geometry parser. Custom Magento module accepts STL/STEP/3MF, parses via numpy-stl or trimesh (Python service called by Magento via REST). Returns: volume mm³, surface area, bounding box, layer count at 0.1/0.2/0.3 mm, estimated print time at 100 mm/s. Cached on file hash so re-quotes are instant.
2. Quote formula. Quote = (material_volume_g × material_rate_per_g) + (estimated_print_time_h × machine_hourly_rate) + post_processing_flat_fee + shipping. Rates by material:
   • PLA: $0.06/g, machine $4/h, ~$8 post-process
   • PETG: $0.08/g, machine $4/h, ~$8 post-process
   • Nylon (FDM): $0.18/g, machine $6/h, ~$15 post-process (sanding)
   • Tough Resin (SLA): $0.22/g, machine $9/h, ~$25 post-process (wash + cure)
   • Nylon 12 PA12 (SLS): $0.45/g, machine $25/h, ~$30 post-process (de-powder)
3. Order routing. Paid order routes the file to your print queue (Octoprint slicer farm, Bambu Studio cloud, FormLabs Dashboard, Sinterit / Formlabs Fuse for SLS). Customer gets order tracking with print-stage updates (queued → printing → post-processing → QC → shipped).

Margin discipline matters: customers will try to game the quote (low infill, 0.3 mm layers, no post-process) to drop the price, set minimum quote = $25 regardless of size so the line stays profitable. Sub-$25 orders eat your batching efficiency.

Lead times sell as much as price: post guaranteed 5-day FDM, 7-day SLA, 10-day SLS turnaround on the homepage. Customers will pay 30% more for a guaranteed deadline than a “contact for quote” bureau.