Try calling upholstery shops, especially ones that do motorcycles, cars, or boats. They'll have a variety of cushioning material; if you're lucky they may give you a scrap.
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"I had a great ride this morning, except for that part about winding up at work."
Bikes so far: 2011 Felt Z85,
80's Raleigh Sovereign (USA),
91 Bianchi Peregrine,
91 Austro-Daimler Pathfinder,
90's Trek 730 Multitrack, STOLEN:
80 Schwinn Voyageur (Japan)
