Hot Wheels Launcher

My son likes to play with the little toy cars and I thought, I'd build him a launcher for his cars.

I started with http://www.thingiverse.com/thing:1802809 but it didn't work out for me. I loved the simplicity so made a design with a similar mechanic.

It's a simple design, just 3 parts, some rubber bands and a cable binder. If you arrange the parts properly and use layer cooling, everything will print nicely without supports (PLA).

Originally I used a printed splint to keep the piston from shooting out. But the splint broke on the first try. So I went with the lazy option and fixed the rubber bands with cable ties.

Sorry for the bad pictures. I printed in black which is not the best color for pictures.

ASSEMBLY:
1) to make it easier, I suggest to hook up the rubber band(s) first.
2) insert the trigger
3) insert piston into the ramp (through the trigger, of course)
4) secure the rubber bands with a cable tie

To load the ramp:
I found it easiest to load the mechani