I modified beam's Mechanical Pencil Gun https://www.instructables.com/id/E46CF748H5EQZJIW1W/ to have an automatic feed with just two rubber bands, a mechanical pencil, and a bic pen, and some around the house appliances.
Step 1: Materials
For this project, you will need:
1 standard BIC mechanical pencil
1 standard PIC pen
2 rubber bands
1 drill with a drill bit the width of the pen
1 super glue or hot glue gun
Sorry I couldn't get a picture of the drill and the hot glue gun. I'm saying this because I am a very visual person and pictures help me very very much.
Step 2: Break Off the Front
Take the pencil and hold the bottom on a table and push against the top which is off of the table. The tip should crack of and the lead will pour out with the other parts of the pencil.
Step 3: Connect the Rubber Bands
Slit the eraser and slide the rubber band through it. Then use the other rubber band to keep the rubber band from sliding. Sounds a little confusing huh? ;) These pictures should help.
Step 4: Take Apart the Pen
Take apart every piece of the pen and lay them on your work table.
Step 5: Drill the Hole
Drill a hole in the pencil about the width of the pen. Pop the pen tube in and glue it in place.
Step 6: Place in the Automatic Feeder
Now place the ink tube in the pen tube pen point first. Wrap a rubber band around the tip. This will push the ammo down the tube into the barrel. You're finished!