+Blow

http://www.thingiverse.com/thing:566713

Materials

In addition to the 3d printed parts, you will need: 

6.5 inches of 2" PVC Pipe 

6 inches of 5/8" x 1/2" flexible vinyl Tubing 

3 feet of 9/16" x 5/8" Nylon Tube (Mcmaster #8628K57) 

3 feet of "thinwall" 1/2" PVC pipe, (ID should be ~0.72") 

16.5" of 1/2" Nylon Rod (Mcmaster 8541K18) or similar 1/2" plastic rod 

8" of "thinwall" 3/4" PVC Pipe (ID should be ~.930") 

1/4" Nylon Rod (Mcmaster 8541K14) or similar 1/4" rod 

1x 1/2" CPVC T 

1x 1/2" CPVC Elbow 

1x 2" PVC T 

6-32 screws in a variety of lengths 

Some duct tape 

At least one Nerf magazine, preferably the 18 round mags. Raider drums won't work.

1)Print one of each piece except for PB4_WingGrip2a.stl -- you need two of those. The parts are in inches, so you will probably need to scale by 2540%

2)Deburr the parts, drill out the large (clearance) screw holes to 5/32", drill out the small (pilot) screw holes to 7/64 and tap them 6-32.

3)Ream the 1/2"-ish hole on the Airblock so that it's just barely big enough to slide in the 1/2" nylon rod without getting stuck, and Stockstarter just a bit more so that the nylon slides freely through the stockstarter.

4)You may need to tweak the model to get useable hole sizes with your printer, most 3d CAD software will open the .stp assembly I have included. The length for PB4_WingGrip2a may also need slight adjustment to grip the Nerf magazines correctly.

5)Use the illustrations as an assembly guide, note that the holes in the breech linkage (parts PB4_FrontGripLink and PB4_BackBreechLink) use set screws to stay fixed to the Nylon rods of the breech and linkage.

6)The magazine squeezer (the almost elliptical part) will need clearance holes to be drilled matching the holes on the wing grips. There is no pilot, you have to match up and mark the holes by hand.

7)The out stop is held to the barrel with duct tape, and the front grip tube is held to the front grip link with duct tape.