https://www.youtube.com/watch?v=i4SJfWCCSno https://www.youtube.com/watch?v=RwRvomvUxvI Hi! This design won "The Most Creative Design" prize in this contest, Thanks to all who involved in this contest! This is my Nerf Dart Compatible Gun (elite), Works By Air Pressure. Slide the Barrel 4 until it's attached to the trigger, and BOOM! ***let me know if you want other dart size*** I hope you enjoy printing it and having fun with it! The good things about my design are: 1- It shoots really strong. 2- Almost all of it are 3D printed parts. About 99%. 3-Full weight after assembly (with screws&nuts+2xcable ties+balloon) is less than 180g. Depends on how durable/stiff you want it. 4- It is nice for kids to learn simple mechanics and have fun in the same time. (parts can be printed in different colors depends on how you/your kid like). 5-Save your money! No expensive parts to buy (probably you need about 1$ to buy the non-3D-printed parts if you don't already have them at home!). You only need: 1- 12x m3/10mm screws (10mm with the cap/flat head), 12x m3 nuts, 1x m2/20mm screw. 2- one big rigid balloon (you can experiment with the size you prefer). 3- 2x cable tie. In this link you can view and explode the model in 3D: http://a360.co/2d06jCi *Parts that need support are only: Trigger, Spring, Barrel 4, Front grip. *Parts that need to be strong with good infill are: Back base, Front base, Trigger, Trigger Extension, the plate of the Front grip. Otherwise you can make everything zero infill if you want.. *Notes: -I lost my 10mm screws bag so I used 20mm instead as you see in the pictures (it should look much better without these long screws). -The test in the video was the very first test, and you can see how strong it is! Even the back cap separated because of the pressure (the glue wasn't dry enough yet). It was a really strong shot although the dart was tight in the barrel!). I re-designed the cap so it doesn't separate anymore. The assembly is very easy as you see: -Just put the barrels inside each other then put the cap in place and glue it so the air doesn't escape (updated version). -Cut the balloon bottom (the big aria) and fit it in the big barrel and fix it with a cable tie. -Slide them in the base and fix the other balloon end in the front aimer with another cable tie. -Put the three trigger parts together with a m2/20mm screw then put them under the base in the place with two m3 screws and nuts. -The other parts just uses m3 screws and nuts as well. -You put the back aimer the last thing by pushing it in its place (it fits tightly). Assembly notes: -The front grip plate should be printed as strong as you can (doesn't matter for the grip itself). You can do multi-infill settings in Simplify3D or other slicers.. -The back aimer should be printed without infill to save plastic. -If your printer can print big parts, combine the front base and back base together and print them in one piece. I used 50% infill and 3 layers shell. -You should print all the parts in the orientation I made, unless you know what you are doing. And don't forget to have a good bed-adhesion for the long parts. -The trigger meddle hole shouldn't be tight on the m2 screw. -The barrels and all the parts fit perfectly if your printer prints accurately. Otherwise you can play with the settings in your slicer and/or use sanding papers. I will continue to improve and update the design. Have Fun and let me know what do you think! Questions are welcome at anytime.