For those who used this material, what cutting instrument is best used to cut this material? Thank you for the help.

Skill saw is what my DH uses.

We use a straight edge such as a pieco of 2 X 4 to guide and cut with an exacto knife. It's not easy but you can be very accurate that way.

To use the exacto knife, you need a heavy duty one & someone with good arm/shoulder strength to make the cuts but it's great for trimming them down!

a heavy duty box cutter

or a very sharp swiss army knife. Also using the straight edge.