Been many years but have used Celcon in the past for a lot of automated machine parts. I think it is a variation of Delrin. It was more dimensionally stable so it machined better than nylon or Delrin. Nylon is definitely low cost.
Yes, I really like the 'old' version swinging chain guide.
I was riding my Kawasaki KLX450R in the Dubai desert a few years ago, it had the solid mounted chain guide, as fitted to most of the latest MX/Enduro bikes...
Whilst riding at speed, I hit a rock that smashed the chain guide and ripped it off the swinging arm, snapping the mounting lugs off the swinging arm. The chain was jammed and I couldn't release it. It was a very hot/humid walk back to the house so I could get my trailer to recover the bike.
I found an aluminum welder who welded the lugs back onto the swinging arm and I got it all straightened out again without too much fuss.
I do wonder... if I had this type of old GasGas 'swinging' chain guide, maybe the damage wouldn't have been so severe. At least maybe I could have limped the bike home?
My 3mm nylon sheet arrived in the post today, from supplier in UK (3euros on eBay).
It looks/feels like the same material as the original.
It's only a small piece but is enough to make 3 pairs of side plates, so will do me for a few years.
I found some blocks of nylon in my garage which I can use to make the rollers. Already did this sometime ago and have been using them for a while now, they work great.
The old style chain guide, with the chain running over a plastic roller, gives less drag/friction as opposed to the new style where the chain runs through a plastic block.
Minimal I know, but every of bit power to the wheel helps!