It is impossible for you to modify the laser pointer that you already have to cut through anything without building such a contraption that it would no longer be your laser pointer, and would have been cheaper to buy a new one.
The 500 mW green lasers at WickedLasers (link) can burn through trash bags, light cigars, matches and other things that are built with ignition in mind, and so on. But as far as "anything" even they are far from accomplishing that feat.
Further, "instant" is not a normal word to associate with cutting through anything, except for industrial lasers versus a piece of paper, something like that.
If you really want to cut through the MOST of anything, you'll need a sealed CO2 3000 W (peak output 1.5 kW) industrial laser cutter. However, if you look at it, even these lasers don't just slice through steel "like a hot knife through butter." It still takes time.
If you really want to have fun, visit Lawrence Livermore Lab., near where I grew up. It currently has a 1.3 PW (1.3×1015 W) laser, the world's most powerful laser. Of course, it takes an entire building to power the damn thing, so showing off at your next conference meeting is probably unrealistic.
Hence, in the end, the best way for us normal people to cut through things is to blow about $2,100 or so at WickedLasers.