I'm building an Ace 30% Extra 230 kit, the plane has balsa sheeted foam core wings and I'm wondering what's the best way of cutting the ailerons out of the wing panels while keeping everything straight and square?
Any suggestions would be a great help.

I use a fine tooth Japanese cut off saw, sand the cut out and ailerons smooth then put the sheeting on those areas. The LE of the ailerons is usually just an angle stock that glues on.

Lay out the aileron on the top of the L/H wing, and the bottom of the R/H wing. Place the foam core shucks on the opposite sides of your layout and cut on a band saw, the shucks will keep everything true to the table and the blade while you cut. It's that simple.

Bob