I don't know the best place to purchase uhmw, but it usually attaches to the to bottom using screws or bolts.
Here's something I looked at a while back. Not sure how well gluing would hold up over time though.
[youtube]LCYDsCs8g28[/youtube]
If you don't feel like watching the whole thing, go to 2:40.
Looks like they also sell uhmw.
https://www.crownplastics.com/polymersprocesses