I saw this post, and waited for a couple of days for the inevitable flames against it. I wasn't disappointed.
I don't get the point of this or any the rest of your homemades. I doubt the accuracy of this thing is all that great, the ranges suck, and it looks like shit. I can't see how this would be very useful in a war.
Could the range be increased by using a bungee cord instead of a string and non-flex CPVC?