Need to make a battery pack for my digital camcorder to prolong camcorder usage. The camera uses 2AA batteries

Try using lithium batteries first. They give the best performance in devices like that. If not, you can homemake a device that conects to the terminals in the AA battery slot but holds C or D batteries. C and D batteries give the same voltage but give more mA hrs (i.e., last longer). I also wonder what digital camcorder uses 2 AA batteries? That doesn't sound like enough at all.

get a recharger and a couple set of rechargeable NiMH batteries - they last much longer than the alkaline batteries and in the long run, much more economical vs. the disposable lithium batteries.