These look absolutely the 'Bee's Knees'. That buckle is an excellent idea - is it along the lines of those that are used on backpacks, hiking gear (and even Mountain Kilts)?

I am very pleased to see that you have left the flashes to run freely along the elastic this time, instead of sewing them together, and to have them interchangeable would be a bonus.

However, I am wondering about the wisdom in selecting just ½" wide elastic. Worn all day, you might find that it becomes rather uncomfortable - a wider elastic, say 1" is less likely to cut into your calf. They do have to be fairly tight to do their job, after all! It's just a thought.