The Family Handyman
Here’s a method that’ll give you great results and keep the lid aligned perfectly as you cut each side. First, cut two opposite sides of your box. Place masking tape over these slots and tap tapered shims into the slots. Next, saw the other two ends of the box. The masking tape and shims will hold the box together as you make the last two cuts.
Caution: Blade guard must be removed for these steps.