I have a spare parts kit I always have with my AR (in the rifle case).  I've got one in 5.56 and another in 6.8.

Each contains:
1) Spare Bolt (fast was to fix most problems).
2) Complete spare extractor & pin (to fixed the messed up bolt when I have time)
3) Spare set of gas rings
4) Spare cam pin
5) Spare firing pin
6) spare firing pin retaining pin
7) 2 spare fire control pins
8) 2 punches (the only 'tools' other than my Gerber).

These are fit into a plastic box not much bigge than a deck of cards, and it fits nicely into one of the magazine pouches on the rifle case with room to spare.

At home I have a spare carbine and all the other spare parts & tools I could need.  And they all fit in a nice Tackle Box (all expect the torque wrench at least).