Mine is a UFO too. Buried somewhere in my stack of experimental blocks. The project is no longer on my to do list although I really would like to make more someday. No need to be scared. You cut the pieces to size like you would do regular piecing, adding a little extra for the outside edges so you can square it up. If you're putting the fabric pieces under the paper, you may want to cut them a little larger and pin or glue them so they don't shift, or even use tape as I sometimes do. Just remove the tape before pressing. For the mini I trim the seams to about 1/8" after they are sewn. The actual width of the diamond is just a little over 1/4". After you get the 8 units sewn, 4 of Unit A and 4 of Unit B, trim leaving 1/4" seam on the outside edges. Remove the paper as it gets in the way. You might be able to leave the paper on for sewing pairs together. It's been so long I don't remember how I did it. The hardest part is getting the seams lined up in the center, although it's really not any different than a pinwheel block.