PVC is easier to work with, but its not very pretty, and it cost like 3x as much as
typical woodworking.
From looking at the picture, I think a single sheet of plywood would have covered
the entire project. At maybe $20 for cabinet grade quality wood, thats about 1/3rd
the cost of all the PVC... And, it would end up looking better.
Of course, it would be heavier, maybe need paint, and take a lot more effort, time, and tools, to build.
I suppose if one found a way to make cheaper joint connections, it might be a little more
cost effective. (though probably not as strong)