This paper describes the design of a verified tool for analyzing tool paths defined in the RS-274 language for 3d printing systems. We describe how the analyzer was designed to allow a mixture of verification and code-extraction techniques to be combined for constructing a correct toolpath analyzer written in the OCaml language. We show how we moved from a fully hand-written OCaml program to one incorporating verified components, highlighting architectural decisions that were made to facilitate this process. Finally, we share a set of architectural lessons that are generally applicable to other software with a similar goal of integration of verified components.