longer carriage for Zheng3 Penny Ballista

I had problems firing my pennys with the (http://www.thingiverse.com/thing:23464) Pennyballista, because the default penny carriage is really hard to grip. In addition the default-carriage don't stays on the track during firing.

So i created a new one on my own.
Works much better now, stays on the track and easy to grip.

Also i adjudest the mount for firing euro-cents.

have fun