There are hundreds of extensions - tools and features - integrated directly into SketchUp Pro. These extensions improve workflow by reducing time-consuming, complex or repetitive processes.
The SketchUp plugins add special functionalities to this simple-to-use design software such as photorealistic rendering, takes-offs and reporting, custom parametric modelling, animation, and advanced drawing tools.
With this in mind, I thought I would list my recommendation of the very basic SketchUp extensions which I’m sure your conceptual design modelling teams and users will find useful.
Here is number one.
Weld - Joins connected edges and broken lines into one continuous polyline

Weld allows you to join multiple connected edges, curves, and/or arcs (by "connected" we mean having common endpoints) into a single "polyline".
The Weld SketchUp extension can be used by the following industries: Architecture, Construction, Education, Engineering, Film & Stage, Gaming, Heavy Civil, Interior Design, Kitchen & Bath, Landscape Architecture, Urban Planning, Woodworking.
This SketchUp plugin is completely free.
Look out for the next extension recommendation. In the meantime, you can explore a few other SketchUp plugins here.
Author
Symetri