EZ Entrie machines[0], first of all, as they've been around for a decade or so and are purpose built to mill one-off high security blanks out of brass, so they're significantly more effective than their plastic counterparts. They are admittedly expensive, but when I briefly had access to one the gentleman running it was cutting me fresh blanks for a Euro a piece. They also have rather jaunty bows with smiley faces inscribed in them.
Additionally, people have been bumping things with just about anything that can fit into a keyway, it doesn't particularly matter if it conforms to the exact shape of the key, so long as it can still interact with the pins directly. So, bent sheet metal with teeth cut into them, flexible grocery loyalty cards, etc. have all been used by folks in the locksport community to bump locks they didn't have proper blanks for. I can't deny the SK6 (and many Ikon locks, they are vicious) didn't have a particularly murderous keyway, but the possibility of carrying out a percussive attack wasn't nil.