Configure-to-order manufacturers hit a wall in ERPNext core: every real product family has hundreds or thousands of valid option combinations, but native Item Variant attributes only capture flat variant axes and cannot express "if frame is stainless then gasket must be PTFE" or "voltage 480V is incompatible with the 50Hz motor." Sales engineers end up maintaining spreadsheets of valid combos, hand-building a BOM per order, and re-keying prices — which is slow, error-prone, and produces quotes that manufacturing later rejects because the BOM was never actually buildable. ERPNext gives you Items, BOMs, Routings, and Quotations, but it has no rules engine to connect them.

We build a proper Frappe app — its own module, installed via bench get-app and bench install-app — that adds the configuration layer ERPNext is missing. At its core are new DocTypes: a Product Configuration Model that defines the option groups and attributes for a product family, Configurator Rule records that express compatibility, requirement, and exclusion logic, and a Price Rule set that drives CPQ math (base price, per-option adders, quantity breaks, surcharges, margin floors). Rules are evaluated by a server-side engine exposed through whitelisted methods (@frappe.whitelist()) over the Frappe REST API, so the same logic backs both the internal desk UI and the customer-facing guided-selling page. Constraint checks run as the user selects, greying out or blocking invalid combinations before a quote can ever be produced.

When a configuration is confirmed, the app generates the concrete BOM — selecting or creating the right component Items, quantities, and sub-assemblies from the chosen options — and the matching Routing/operations, then writes a fully-priced line onto a Quotation (or Sales Order) with the configuration snapshot attached for traceability. We wire this in cleanly using hooks.py doc events (for example on_submit of the Quotation to lock the configuration and validate to re-check rules server-side), Client Scripts for the interactive desk experience, and scheduler events where background recalculation is needed. Role Profiles and DocType permissions gate who can edit models and rules versus who can only configure and quote, and everything is version-safe against ERPNext/Frappe v15 and v16.

Because this is build-to-order, there is no instant download. After a short scoping call we map your product families, attributes, and pricing logic, then build and configure the app against your data on a staging bench. Typical delivery is one working week from confirmed scope. You get UAT on staging, a rollback plan, the full git repository, and a post-go-live support window — the configurator is fitted to your actual products, not a generic template you have to bend to fit.