When I first bought my loom 7 months ago, this project looked absolutely impossible! But in reality it was not different than any other overshot project, just a larger draft and treadling sequence.
The weft is 12/2 cotton light gray blue, but I treated it like 10/2 like the ladies in the yarn store suggested. I am unsure of the brand, it is a HUGE 3 lb cone and that's about all I can identify about it. I made a 4 yard warp and wove 20 epi. At first I tried the overshot weft with 8/2, but it didn't seem square enough so I changed to 8/4 and it was perfect! I have one in navy (as shown), red, and brown. My favorite is the navy!
My plan is to enter this into the county fair this fall and maybe save the other 2 for gifts.