New customized "Find" button

I'm trying to create a Find button that will look in a particular folder for any filenames that have a user supplied pattern and do not have certain file extension(s). I came up with this:

Find in "%DataDrive%\Users\Bob\Documents\foldername" Name "{dlgstring}.*" Quiet ShowResults=Output

It works but is also does not allow me to exclude certain extensions. I tried using the NOT symbol (~) as described in the manual but didn't quite know where to place it and I ended up not getting any results. My intention is this:

Click the button, enter findthis, and receive results of all files that have findthis in the file name as long as the file extension is not (xxx|yyy|zzz)

Any help would be appreciated.

"{dlgstring}.(~(xxx|yyy|zzz))"

Note that (like the command in the root post), this will not match names which have no dot/extension at all, e.g. most folder names.

Thanks Leo... I was close but had my parentheses in the wrong place. I only need files, not folders but I will keep that in mind.