There are five pieces of foamed PVC here:

large piece with holes for the screen frame and a cutout for the "cartridges" trim piece above the trackpad trim piece below the trackpad top "nose" piece bottom "nose" piece

Most were cut to width on a table saw, with any odd angles cut on a band saw.

The trickiest part of construction, by far, was getting the "nose" (the angled bit of the case in front of the keyboard/trackpad) right, so do that first. I printed templates from the sketchup file to get the angles at the ends of the nose pieces as close as possible; the width was off a bit, so adjust as necessary. From there it was just a process of sanding and tweaking until things fit.

I cut a piece of wood on the table saw angled in such a way that it reinforces the nose from inside. It's held in with hot glue; I was nervous about doing that but it worked fine. You might see in the pictures I also used finishing nails to hold the pvc board to that wood; I'd recommend NOT doing that. It was really hard to hide later.

The thin strip where the top and bottom nose pieces come together is filled with wood putty and sanded smooth. I had plenty of other wide gaps (e.g., where the nose pieces met the case sides) that also got the wood putty treatment.

The other case pieces were pretty easy, since they're rectangular. Mostly they are held on with super glue and small wood brackets. Hold off on gluing the PVC pieces until the absolute last, though, just in case you need to adjust the fit. I used lots of hot glue and blue painter's tape to hold things in place temporarily (the hot glue can be scraped off fairly easily). I printed a template from the sketchup file to locate the holes in the big top piece.

I've included my Sketchup file if you want to play with it to get dimensions, modify for different parts, etc.