There are a few things to consider while creating your templates. We will look at them and break them down into factors.
A safety edge is where you would fold the sheet metal over onto itself as to create a blunt edge that cant cut.
Square edges refers to edges that are 90 degrees to each other (perpendicular)
Parallel edges refers to edges that never intersect each other and is always has the same distance between them.
It is important to know what a safety edge, square edge and parallel edge is when creating templates from paper and cardboard.
Use a set square to create square corners and square edges.
Use a ruler to measure edges and create parallel edges.
Use a compass to create round edges.
These tools are used to draw your template, and you need to know how use them.