He never mentions what the part is going to be used for, but at 376 x 376 x 250mm (14.8 x 14.8 x 9.84in), he estimates that this is the biggest single part printed with a DIY 3D printer.

The answer is simple: DIY 3D printers done right are rugged workhorses. They work every single time, they never break, and even if: they are an inexhaustible source of spare parts for themselves.