John in NM
For general use, tightish fit use any 5 minute epoxy. I used to buy this stuff at Home Depot that was made by Pacer Technologies (a big super glue outfit) but they stopped carrying it.

I don't like all 5 minute products, the most recent I bought was a JB Weld brand and one component is so stiff that the two halves don't push out at the same rate, guaranteeing you an uneven mix and a tacky cure.

For filling large voids (like threads in a plumbing nut used as a ferrule) use a paste epoxy like either JB weld or PC11 marine epoxy paste (that is the one I like since it's whitish and transtint blends in making a good filler putty). For PC11 you can use denatured or isopropyl alcohol to clean up uncured epoxy (and it cures overnight).