Teflon adhesive anyone?

Absolutely impossible with Teflon. The only way is a nasty chemical conversion treatment of the Teflon surface into something bondable. You can order material so treated on one side from mscdirect.com. Search for "bondable ptfe". Ordinary epoxy will then work quite well.

There are some adhesives promoted as having several hundred psi of bond strength for Delrin, but lack of peel strength is a problem. In any case it's a tiny fraction of the strength you'd expect from epoxy on easier materials. But it is more than zero.

There are many adhesives that work with the "other plastic" you mention, but none that I'm aware of for Delrin and the like. You may want to try heat welding them.