Then they used Google Shopping to determine the maximum and minimum cost of buying those 20 items online, shipping charges not included. Next, they calculated the cost of making them with 3D printers. The conclusion: it would cost the typical consumer from $312 to $1,944 to buy those 20 things compared to $18 to make them in a weekend.
Oh come on. Like all those items online were made out of the same low-melt-point plastic and the 3d-printed ones were of equivalent quality. I'm very much pro 3d-printing but there's some serious reaching here.
The last page of the study (http://www.academia.edu/4067796/Life-Cycle_Economic_Analysis...) offers examples such as a shower head with prices ranging from $7.87 to $437.22, jewelry organizers from $9 to $109, and orthotics ranging from $99 to $800. There's a little bit more going on with the expensive ones than just being a heap of plastic that you can duplicate at home, I think.