I wouldn't suggest drilling a hole in a normal 12 gram. They've been known, to sometimes be not as strong when you do that, and could injure you.
While it's a bit more spendy, than the "do-it-yourself" dummy 12 gram, it's a lot safer.
I'm not too familur with the Delta 68, but my Ariakon Overlord had a small hole at the bottom, where the 12 gram tube is, that's threaded for an adapter for your macroline. Then the macroline runs down to your ASA, and viola, you have constant air. I'll try to find a post about it, and let you know.