With this and their router bits with guide bearing it is hard to mess up. A creative idiot could mess it up, but with due diligence results ought to be great.
I haven't used it yet, but have used other stew-mac templates. They are all great, you just need to take your time, and learn how to use them properly. It is also a great idea to make thicker templates out of MDF first, because if you mess up your master templates, you'll have to order new ones.
I used this template to install two dual-battery boxes into two different guitars. It worked fine, and the battery boxes fit well.
Have yet to actually use this... not many battery box install jobs coming in, but i'm sure i'll love it.
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