I am not the maker, but perhaps I can still help you. I am also planning on making a large printer (over 100010001000mm building volume). I will be basing the hardware on the Bigrep one.2 and the electronics and software on this build. Since I am basing the hardware on the bigrep, I will be using much higher quality, stronger and more reliable components than in this build. You can read more about it on reddit: https://www.reddit.com/r/3Dprinting/comments/bd0q3s/making_a_large_scale_3d_printer/?utm_source=share&utm_medium=ios_app.
Feel free to add comments on my reddit post.