In reply to edhawk21:
I use a Keep Cup (original 12oz model) with a neoprene 'can cooler' around it. It's small, light, tough and keeps a brew warm while you're drinking it, even outside in the cold/wind. You can't leave it in a rucksack but is fine for drinking from in a moving vehicle.
Then there's a contigo push button mug/flask thing that I use occasionally. It's an older discontinued model but doesn't leak.
The former if you just want to make a drink and drink it there, the latter if you want a hot drink you can consume over a couple of hours whilst on the move.
If you want it to be for alpine/bikepacking then I'd suggest one of the flask types would be too heavy.