I don't have window seats but I did want to make cushions for my porch swing, metal bench and 2 wicker chairs. My sister had given me this large piece of sponge she used to have on her bed so I kept it knowing some day I'd find a use for it. I ordered some outdoor fabric for my projects since they'd see the sun part of the day. I made a cushion cover out of muslin and used it for a pattern for the actual cushion. For the cushions/pillows with ties I just used some my mother had given me. My cushion for the swing is a box style cushion so I added a long zipper on one edge plus ties as we have high winds around here. I also made it reversible too. I quilted the fabrics before I assembled them, then cut to fit. Also made cushions for my little deck table chairs and recovered my folding chairs to match. With leftovers I made a table cover and added an embroider design in the middle. All in all I was quite happy with the outcome. All cushions for the chairs can also be removed from the cushion so they can be washed. Sorry couldn't find my deck pics,must not have taken any.