If this is a one off request then I think I'd take a pragmatic approach.
First copy all the design names and repeatedly paste them to the next blank row in column A for as many times as there are sizes less 1. In this example 4 sizes so copy the names 3 times to A6, A10, A14

Now copy each of the columns B2:B5, C2:C5, D2:D5..etc to B6, B10, B14

Finally filter B for blanks and delete these rows.