I warped my rug with a couple of weights of crochet cotton. Size 3 crochet cotton (the Aunt Lydia's brand is commonly available) is a great warping material. Since I only had about half of what I needed, I interspersed it with some lighter weight crochet cotton just to see how it would work. In retrospect, the size 3 (which I think is also known at #10) is the perfect weight. Note to self: stock up.
The numbers: 170 warp threads in the 7.5 dpi heddle, 58 inch warp length. In the future I'll need about 2 balls of the Aunt Lydia's Size 3.
For the weft I used 2.5 inch fabric strips. Quilters may have a few of these around the house. Join the strips (and avoid knots) by applying glue stick to 1-2 inches of the end of one strip and overlapping it with the next one. Let it dry 20-30 minutes and then fold in half along the length and wind onto a shuttle. I chose a palette of blues and yellows. I'm not sure how much i used, because I have an endless supply of 2.5 inch strips.
In this rug I alternated two passes of the fabric with two passes of worsted weight ("kitchen") cotton. I used less than a ball of Sugar and Cream for this rug.
The whole project is beaten with a comb. The heddle isn't strong enough to pack the layers together.
When laying down the rows, twist the fabric at the edges. I only remembered to do this at the end. When beating with the comb, I found that I could only really pack in the rows after changing the shed (the position of the heddle). I found myself working the immediate 4-6 rows, packing them in, while adding new rows.
In the photo above you can see that the new rows are more loosely packed than the previous rows. They'll gradually get worked down after newer rows are added.
The finished rug is 20 x 25 inches. I tied off the warp threads in groups of 4, In the future I might add additional passes of the kitchen cotton and turn the hem to the back. I washed the rug to make sure it will hold up to delicate machine washing, and it came out fine.