i've experimented with natural material[leather]+rubber on the brompton
so far the results are better than the stock elastomer which is too springy
here's how it looks:
you add leather or rubber rings to get the desired dampening
for the seat I prefer the damping properties of real leather like the brooks b17 or b67[with spring] I think leather[skin]
and human skin have about the same characteristic or properties that they work great together as opposed to other materials molded plastic, foam, metal springs or
polyurethane dampers which has different elasticity as our posterior. Latex/gum rubber is my next preference just my opinion.
shock absorbers using oil instead of polymer/spring are also great but they significantly add to cost and complexity, weight and maintenance.
Good ole leather material as ancient as human history is not obsolete in my book anyone wants to wear vinyl shoes instead of leather shoes ?
even with cycle clothing merino wool jerseys is my #1 preference but thats another story