My H1B always had a pattern humped seat cover from when I first got the bike. The seat rotted away over the years, but I could only find flat ribbed coverts and and being used to having a humped cover, to my eyes they have always just looked wrong.
I found a good quality seat cover on Ebay from 'bob the seat' which had individual compartments for each rib with a bit of padding inside.
So I got some foam pipe insulation, cut it into sections and inserted it through a slash made down the centre.
The piping broke at it's seam creating a fold I couldn't get rid of by stretching
I used some old hardened wire glued to the insides of the seam to bring the piping back into line and get rid of the fold
The two ends of the piping was cut back to allow them to line up and the gap filled with black silicon
The finished article - just like I used to have fitted