Step 1: Gather the materials
Step 2: Cutting materials to size
I used the horizontal band saw to cut the square tubing to 14.5 inches (a little longer than the folded towel length).
Then I cut the rod with the chop saw. Based on the materials I had on hand, I used the longest dimension of the 3/8" plate (the diagonal) to get the length of the rod.
Finally, I used a tin snips and file to get the end caps sized correctly (just a hair smaller than the outside dimension of the square tubing).