How is this done? Have seen it on Cake Boss, but never attempted it. Tried to find any info on here (cuz I know there HAS to be something!) but it's not coming up.
TIA!

You can use either a diamond cutter or a square cutter. Match up the ends and just keep going till you've finished the whole cake. I would start in the back of the cake so if they don't match up perfectly, it's in the back.

They make a diamond impression mat, but it appears that the guy on cake boss actually uses the quiling tool (wilton makes one for beginers) and a drafting triangle.

I just use the impression mat and its worked fine for me so far.

I actually did a bit of a quilted look in a pillow cake i made (its in my pictures) and to do that I just cut a long strip of paper and laid it over the cake in diagonal pattern and marked along the paper with the back of a paint brush.
Its probably not the "best" or easiest way but it worked for me when I didn't have any special tools for it.

I prefer the quilting roller and drafting triangle because you can change the width of the quilting whereas the quilting stays the same width when using an impression mat.

I've been to chicken too try the drafting triangle for fear that I would change the width of the quilting inadvertantly on the same cake lol.

If you mark the spaces just slightly when you measure around your cake, then you know exactly where to place the triangle each time. Like if your cake measures 20" and you want 1" diamonds, then place a tiny little mark at the bottom of your cake at every inch. This is where you will line up the right angled corner of your triangle.

I just took a class with Jennifer Dontz and she had diamond shaped marker that look like 3 diamonds in a line. Jennifer had 2 differant sizes, a smaller size and a larger size. Jennifer stated that she starts in the back and then adjusts as she is going around if needed to make all appear if it lined up perfectly.