Always get a second opinion
Some time ago i wrote a piece about a "bent" i was building. In it i mentioned that i was using nonmetalic Sch40 as part of the seat frame. A"knowit all bike builder" told us all that i was wrong to use the material; that it was heavy, would require additional reinforcement and that he had failed in an attempt to use the material. Turns out he was not correct. The seat is not heavy, has only two mounting spots, a slidding foot below my rumpt that mounts directlly to the main frame and another that ties in at the donor bikes seat tube. In addition to providing additional strenght to the semi-hard aluminium seat panel the sch40 provides side support to the rider upon which a fabic cover makes a nice bolster. the two parts of the seat were fixed together with a couple of screws and a handful of poprivets. So the moral is...you guessed it always get a second opinion. There are lots of them floating around on this webb site.