I’ve only used the aluminum connectors and they are build well. Their mounting clips can be used on other panels as well. The ebay store is the way to go. They will even cut it to size for you.
When I finally get around to it, won’t be soon (I ususally ask and research really far ahead 
) I will def. post info etc. but my bet is that others looking to do this will beat me to the chase…
random thoughts on homebrew high-temp fans.
Blower squirrel cage fans I think normally have the cage mounted in a unit separate from the fan.
actually, I guess any motor with a separate fan will work, so you don’t cook the motor.
just need to add a bearing of sorts (even teflon blocks) to mount the shaft through the oven wall.
Squirrel cage Fan;
This is the motor mount;
The only reason I had the pullies instead of the direct drive motor was in case I had the fan speed wrong, then I could change the ratio easily.