This is based off of the very excellent Foam Dart Pistol from vik. I couldn't achieve the desired height with the Thing-O-Matic that I wanted, so I modified the design to have a separate muzzle. I added a sight to the muzzle to facilitate putting the two parts securely together. The muzzle piece actually goes on and stays in place without glue, especially with the rubber bands in place.I added the matching sight parts to the back. of the gun, and updated the openscad to have optional mouse ears to keep parts down better. I needed the ears with the ABP, but not with a HBP. You can see the ears on the blue muzzled gun. My wife thought they gave the gun a sci-fi look, so she wanted to keep them.Early testing showed that the firing pin quickly chewed into the front of the barrel. So I added a second set of blocks (that will also work with the original design) that can be glued on additionally, and replaced with wear. They also support rubber stops nicely. I used cut up pieces of a rubber washer.This came about because, I had a lot of trouble printing the pistol at first. Turns out it was mostly due to my ABP on my Thingomatic allowing too much sway. I took off the belt, and have a quasi-HBP now. My prints are much more accurate, especially when printing so tall.Use the STL files to print the parts, or the openscad file to decide which parts to print, or to add mouse ears to help hold the pieces down.Basically the same as the original Foam Dart Pistol with the following steps:I also had trouble with the melting of the filament for holding the sear and trigger, so I just opted for modeling glue, and it works out better for me.For assembly see the video here: http://www.youtube.com/watch?v=auKLBw5P9bQ