Gravity-proof marble pumpgun Hello dear community, today I had a cool idea for a slingshot, that a friend and I want to try building. The idea is based on the M10 Hex-nut shooter by joerg, and somewhat refined. I made a rough model of how it should function, but note that the dimensions are absolutly random, so this is not a building plan, it should just give an idea. Since I am not very familiar with google sketchup so far, it may not be perfect, but you should get the idea. This is, what my initial idea was: The plan was to use the toothbrush (red) methode by joerg, to hold the marble (blue) in place. Also, since I am not sure, if a paracord can push a complete round marble, i decided to use a wooden block (green) as a "pusher", and tie it to the theraband (gold). After a little refining i came up with this: The special thing about it is, that the "holder" for the marble collapses into the bottom of the barrel, as soon as the trigger is pulled, so that the wooden pushblock can accelerate the marble and shoot it out. Also i added a device, that pushes the marbles in the "magazine" back, so it can be cocked even if the pumpgun is pointed downwards. The marbles are therefore filled in from the top, after the pusher is pulled forwards You can download the model via Google drive, if you want, an honest opinion would be much appriciated! https://docs.google.com/file/d/0B3PTFJI1SVXCQXdFRUxialA2YkE/edit?usp=sharing Also it would be awesome, if anybody would be able to build something like this, or just use my ideas as inspiration and post this here! EDIT (20.06.2014, 01:13h): OK, i did some refinement, and this is basicly how i want it to look like: Here is the sketchup of the new version: https://docs.google.com/file/d/0B3PTFJI1SVXCN05wYW9xQlRGdTg/edit?usp=sharing "Hope you like it, thanks and by by!" But now it is late, and i am going to sleep! EDIT: fixed the worst typos, now it sould be at least readable!