: Wouldn't you want it to be simple though? The first video above makes a point
: of saying you can assemble and disassemble the gun without tools, and if
: you feel you need one you can just use one of the rounds it fires, and
: I've heard that said about other guns before. Mechanical attachment is
: robust too, it's relatively easy to make it strong and durable. They could
: have some futuristic thing that works as well or even somewhat better and
: is just as easy to use but there might be an issue of cost.

Picatinny rails are great and simple, don't get me wrong. Their pros definitely outweigh their cons.
That said, they're still grime-magnets that tend to catch on everything, and you need tools to adjust them. Room for improvement.

: Did you have something in mind? I don't know what they could use besides some
: kind of rail attachment, latches, hooks, screws, or magnets.

I was thinking of something along the lines of magnets, or perhaps something more exotic. Perhaps a smart material that 'spot welds' itself in place when you run a low-amperage current through it, and then breaks apart when a reverse current is applied.