Quote Originally Posted by nesman85
i heard a guy say once that he took a pen and melted it, then stuck it in the screw hole of an nes cart to got the shape of the screw imprinted into the plastic, then he was able to unscrew a few carts with it.
That could work but you'd need a thin pen for NES games. The common pen you get a dozen for a dollar are big enough for larger security screwsd found on most consoles and most Sega carts but it won't fit the hole on NES cart.

Another tool that could work is the spanner (looks like 2 pointed fork, commonly found in a $10 security bit kit at most hardware stores). You'd probably need to use a small hand grinder (like Dremel) to adjust the width of the space so it'd fit the security screw.