No dimensions are given here as you will have to measure your own machine to fit. Be sure to make the lip at the front a bit larger than I did to hold the laptop securely in place. The top edge of each piece is covered with a slice of rubber from a modelshop, I used Araldite 2-part contact adhesive to attach this, it hasn't worked all that well.
The holes are drilled for lightness and airflow, you could be clever with this in all sorts of ways but I wanted to finish quickly.
Making tips: cut the holes with a hole cutter(if you have one) not an auger bit as this will splinter the ply. Don't cut the holes too big or too near the edges as this will create weak points.
that's it really.