Summary

Hopefully this will be prototype 2's final design. My printer has been broken for a while, so I have not actually tested any of the changes I made after prototype 2. If you have any trouble, Email me or Ping me on discord and I'll see if I need to make changes. Any changes will probably just be tolerance issues.

"Call your hits", "Boomchacle's Boombox", "Foam Storm", and "Black box" are suggested names that I think are fun for this blaster. It has "Call your hits" embossed on the side.

Description: This is a 25 barrel, Semi/full auto blaster which is supposed to fire individual barrels as you pull the trigger back. If you pull the trigger fast enough, it fires a single blast like a shotgun. Be careful! This is a prototype slingshot, and i do not know how reliable the trigger system is. Do not ever load it with anything that could be dangerous, and never point it at your face without safety glasses.

Primary hardware list:
Either a bottle of super glue or your choice of solvent for welding your plastic.
Sixteen M3X25 mm screws (can be longer, up to 35 mm if required) Link https://www.mcmaster.com/91292A020/
Four M3 nuts Link https://www.mcmaster.com/91828A211/
Seventy five Rubber bands (#32 or #33. Staples usually sells these, or you can get them at mcmaster. https://www.mcmaster.com/12205T54/)
A bunch of 1.75 mm filament
Light silicone oil

Alternate hardware list:
Either a bottle of super glue or your choice of solvent for welding your plastic.
A bunch of 1.75 mm filament
A bunch of tape
Seventy five Rubber bands (#32 or #33. Staples usually sells these, or you can get them at mcmaster. https://www.mcmaster.com/12205T54/)
Light silicone oil

Tools required:
Side cutter or some sort of filament cutting tool
Allen wrench if you use screws
A stick or dowel to push the dart sleds down the barrel.
Clamps or weights of some sort

Assembly Part 1. Magazine assembly.
Required parts: Dart sled, Dart sled latch, Magazine, Bunch of Filament, silicone oil, glue, rubber bands.

Step 0. Clean off any brims from all of the parts.
Step 1. Referring to the Sled Latch. Put a drop of silicone oil on the wavy crack, then lightly stretch and slide 3 rubber bands into it.
Step 2. Align sled latch with dart sled and insert 1.75 mm filament. The "latch" part of it should face the rounded side of the sled.
Step 3. Apply a drop of super glue or tiny amount of solvent to the filament in the hole and let it sit for a few hours to dry off. One magazine requires five of these.

Step 4. Referring to the magazine. Slide a length of 1.75 mm filament through the holes above and below the muzzle exit. Cut them off so they sit flush with the walls of the magazine. Repeat for back side, then put a drop of super glue or a very small amount of solvent on to prevent them from falling out.

Step 5. Once the dart sleds are dry, wiggle the latch around to make sure it works. Push a dart sled latch first down a muzzle, keeping light tension on the rubber bands. If it stops before the latch exits the rear, pull it out and flip it so the latch is inverted, then push it down again until it exits the rear. While applying tension, the latch should snap into place and lock, however priming it without the priming comb is inconsistent so it may not actually lock to the back. Repeat until the magazine is full.
Step 6. Now take the rubber bands and string them around the back, so they slot into the deep groove.
Step 7. Put a bit of silicone oil onto the rubber bands, especially on the muzzle end right where they rub on the filament strand.
Step 8. Test the magazine by pushing the dart sleds back with the comb. They should lock back in place. If it's too awkward of a position, you can prime a single barrel at a time by using the edge of the comb on the outermost barrel and working your way inwards. Just be careful not to torque the end of the barrel, or you can crack the 3D printed barrel along the thin section.

Assembly Part 2. Handle assembly.
Required parts: Left and right handles. Glue or solvent. Short alignment pegs. Some sort of clamping mechanism.
Step 1. Take the handle which has been labeled "call your hits", and put a short alignment peg into each hole on the cut half of the handle.
Step 2. Take the other handle and make sure it lines up with the pegs and can go all the way down.
Step 3. Take the handles apart, apply copious amounts of glue or a light amount of solvent to the flat face, then clamp the two halves together. Take care to avoid the smaller diameter through holes. If you are going to use filament pinning, run filament through the small holes on the top and bottom to make sure they don't get plugged.
Step 4. Let sit for a day or so.

Assembly Part 3. Cover assembly.
Required parts: Long and short cover plates, long pegs, glue or solvent.
Step 1. Insert long pegs into the holes on the front of the long cover plate.
Step 2. Slide the short cover plate onto the exposed pegs so both of the flat sides of the cover plates are facing the same direction. You should see a continuous grid of holes on the other side.
Step 3. Pull the cover plate back a bit, glue/solvent it up, then slide it all the way in again until there's no gap between the two cover plates.

Assembly Part 4. Main assembly.
Required parts: Previously assembled parts. Short alignment pegs. Long alignment peg. Trigger. Automatic fire plate. Automatic fire plate cover.
M3 screws and nuts or 1.75 mm filament and tape.

Step 1. Take one of the assembled covers and put short pegs into the grid of 12 holes.
Step 2. Put an assembled magazine assembly on the grid, with the muzzle side lined up with the outer edge of the cover and facing upwards. The upwards side is the side which the latch grabs on to.
Step 3. Repeat this step with the next magazine and stack all of the magazines on each other full of pegs. You can glue the pegs by themselves into the magazines to make it easier to take out without the pegs coming loose, but DO NOT GLUE the magazines together. They need to be able to be taken apart in order to replace rubber bands and for maintenance if it jams.
Step 4. If you are using screws, Put M3 nuts into the slots on the Automatic Fire Plate cover's slots near the top and bottom. The top is the side with the open ended slot.
Step 5. Slot the Automatic fire plate into the Automatic fire plate cover. The long extruding part of the Automatic fire plate goes into the open slot, and the two short extruding parts go into the closed hole side.
Step 6. Put a rubber band over one of the automatic fire plate cover's small extrusions, loop it around one of the Automatic fire plate's small extruding part, then pull it back up over the second small extrusion so the rubber band pulls the automatic fire plate towards the open end.
Step 7. Put the Automatic fire plate and cover on the current stack of magazines, so the automatic fire plate faces the back of the magazines. Hold it in place so it doesn't fall over before the next step.
Step 8. Put the handle in place, then put the top cover on so it sort of clips on to the magazines and their alignment pegs.

Step 9. If you are using screws, insert the screws into the side of the cover plates so they slot into the handle and lightly tighten until you feel resistance. DO NOT OVER TIGHTEN. The screws are only there for alignment, they do not need to be extremely tight. If you over tighten these, it may split the glued connection. There are 12 screws in total here.
Step 10. If you are using screws, Insert the screws into the top and bottom of the cover plates so they slot into the M3 nuts in the Automatic fire plate cover and snug it up, but do not over tighten. If you over tighten, you may split the plastic of the Automatic fire plate cover along the layer lines.

Step 9 Alternate. If you are using filament, pins, slot 1.75 mm filament through the line of small holes on the sides of the cover plates into the handle and cut them flush. A drop of glue may be required if they're still loose, but if they start to get tight, it may not be required. There are 24 of these holes, but that might be overkill. It's just for redundancy to reduce the stress on the filament pegs.
Step 10 alternate. Wrap tape around the front of the blaster such that it provides substantial tension. Wrap it 3 or 4 times around, holding it tight every time.

Step 11. Push the trigger up through the trigger cavity and push a long alignment peg through the LEFT handle. It should get tight, but if it doesn't put a drop of glue on the peg. When you push the trigger down, it should push the Automatic fire plate down. The trigger should be able to be pulled all the way back to the handle.