I just made a bicycle seat which is similar....I looked and looked on way to do this....I took the best ideas from everything I read first I cut out my pattern/ top & sides I used 4/5oz.. 2nd I tooled the leather.. 3rd I laced the sides to the top...4th I wet-formed the leather to match the contours of the seat pan...5th I glued the leather to the pan(make sure you use waterproof glue) and rivit/staple the sides under the seat and trim the bottom.. 6th oiled....7th I dyed it....8th super sheen....hope this helps