With this in mind, it's interesting to look at the "set design": miter saw, clamps, drawings, sand paper, wood scraps, sawdust and broom all strategically place

With this in mind, it's interesting to look at the "set design": miter saw, clamps, drawings, sand paper, wood scraps, sawdust and broom all strategically placed around the scene to add realism. For giveaways thought, in addition to the strange shadowing and textures the parent mentions, there's the human factor. To me the acting seems just a bit off. Kudos to the guy who made this though; I imagine just modeling that structure (and its shadows and reflections) in CGI was a fun nut to crack!