Sheet metal function is very useful since you can design according to your need, so if you know that your machines have limitations, you can plan ahead to limit them. Below is a simple tutorial on how to create a very simple body and then flatten it to check its pattern
Start by creating a sketch for the base. I'm making a 75x75mm square
Then using the "base flange/tab" feature create the base for your body
Since our base is looking good, next step is to add in the "edge flange". Note that you dont need a sketch, but can use just the edges. I'm adding 2 flanges to the sides
Select the "edge flange" again
Select the inner edges of the recently added flanges and from the left side add a gapdefault is 1mm)
After accepting the changes, and adding the 2 new flanges(having a total of 4), we can now use the "flatten" option to see the pattern. Great for estimating costs :).
Great job, go and try to create a more complex body and see how it works :)