On Saturday, January 17, 2015 at 6:21:33 PM UTC-8, John Doe wrote:
I do a lot with 6061 aluminum, without welding.

What's the best glue for aluminum?

Hotmelt glue, of course; a zinc/aluminum alloy, called 'aluminum solder'.
Surface prep, and positioning/holding while the glue is liquid, are the big problems.