Dutch,
I was surfing another forum and saw that a guy used flexable drywall bead for barriers, and it looks pretty cool. Looks like you could pin it in whatever shape you wanted to your track. He stated it was $1.25 for an 8 ft section. See some pictures of the track and barriers here:
http://home.wi.rr.com/cdconsulting/M...ack%20Pics.htm