A system can receive selection of endpoints for a spool on a graphical user interface (“GUI”) and attempt to assemble a spool based on the endpoints. To do so, a plugin can execute a route-finding process that traverses routes from the endpoints. The routes can be determined by retrieving connectors from the endpoints and, for each connector, determining what parts are connected. For each connected part, the process can repeat so long as the connected part is not one of the endpoints or already in another route or spool. When the routes are complete, the connected parts can be treated as an assembly of the spool. The GUI can generate a spool sheet that uses the assembly as the spool.