Engineers often face challenges in modeling Software as a Service (SaaS) products' pricing and packaging using Stripe, especially for usage-based scenarios. This guide helps translate SaaS pricing and packaging concepts into Stripe entities by defining products and prices, applying tiered pricing, using meters to manage prices, packaging prices for customers and subscriptions, and reporting usage. The example used is a hypothetical Twilio-like API-driven SMS/MMS-sending service. By understanding the process and utilizing appropriate tools like OpenMeter, implementing usage-based pricing with Stripe can be simplified.