You can access a few example .blend files from DECALmachine's help panel.

Decals

Decal Basics

Decal material features, material matching, mirroring and joining

Create Decals

source geometry for the creation of all 4 Decal types

Bake Decals

very simple decaled object ready to be baked

Decal Demo Asset

simple decaled demo asset

Trim Sheets

Trim Sheet Geometry

geometry used for Example Sheet creation

Trim Sheet Setup

trim setup of the Example Sheet

Trim Sheet Demo Asset

Example Sheet demonstration