In Core, every object in a game is ultimately made out of pieces of Core Content. We use the term kitbashing to describe the process of taking apart pieces of a kit, and using them for a new purpose.
Creators can make games entirely using the finished props provided by Core in the Core Content window and models made by other creators in the Community Content window.
You can also make your own props and structures by modifying Core objects, and grouping them to be treated like a single object. Packages of these groups can be shared as open-source Templates.
Modifying the colors and patterns on a 3D model is the easiest way to change the appearance of objects. Materials can be added by dragging and dropping them onto an object, and adjusted through the Properties window.
You can also make a custom material, which will save your modifications to the material, and update them for any object the custom material is applied to. See the Custom Materials reference in the Core documentation to learn more.
Creating a group allows you to put together multiple 3D objects into a single piece. that you can copy and manipulate in one piece. Toggle Group Selection Mode by pressing the C key to swap between selecting the whole group, or the individual objects within it.
You can learn more about different ways to group objects in the Core documentation modeling reference.
Using a template will allow you to share your new model on Community Content, as well as to group it with script functionality (like a weapon), and pass copies of it between project.
To create a template, right click a group and select Create New Template From This.
To learn about how to publish your template, or use it in other Core projects, see the Core documentation template reference.