I realize this was asked a year ago but for future builders…you really should use a jigsaw for this. You can pick one up for $20-30 and they are very easy to use. Measure the cutout and draw a nice straight line and it will be pretty easy to follow with the jigsaw. You don’t need to worry too much about how nice and straight you cut the edges on any of the 4×8 sheets because they will all be covered with trim. The plans don’t include trim to cover the bar rail edge but they do mention it and you will want it.