Suppose I have a list of structural beams.

W6x15
W24x207
W6x15

What I want to accomplish is to have a new list of the beams in descending order of the depth first, W, and then the weight per foot, number after x. My initial attempt was create a main dictionary containing all the W sizes. The W sizes would themselves be a dictionary where each would contain the weight per foot value. So essentially I would have a dictionary with two dictionaries 6 and 24. Dictionary 6 would have items 15 and 207. I figure that for each W dictionary I can write a piece of code that would sort in descending order the weight per foot. Then in the main dictionary I can sort on the W sizes in descending order. Is this a good approach or is there something better I could do?