Batman is commonly misconceived to be able to do absolutely anything on his own, but he's often enlisted the help of other Justice Leaguers or gone to other professionals for work outside his direct expertise. Even then, he does come up with the plans, applications for tech and counters for enemies.
That's not to minimize his capabilities, he is one of the smartest Leaguers there is, but there are others that are smarter. Mr. Terrific, Ray Palmer, hell, even Superman is way smarter than people give him credit for and he's helped Batman build some doohickeys and come up with plans in the past.