Introduction: Lead-feeder

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I am a lazy person. I’m so lazy that I don’t even want to refill the lead. After refilling, my hand would be covered in lead (the chemical element). Since I cannot endure dirty things like lead on my hand, I always need to clean my hand after refilling. It’s tiring. Besides, when I am in a hurry, it’s like anxiety for me to refill in a short time while trying to avoid touching the lead by covering my hand with the tissue. Therefore, I designed this machine, which I can refill without touching the lead even in a short time.

When the RGB LED show the color green, it is ready for you to put your hands inside it. After you put your hand into the machine for 1.5 seconds, the PIR Motion Sensor would detect your hand and RGB LED would show the color red, the lead would start dropping out of the mechanical pencil for 10push of Linear Solenoid Electromagnet. After dropping, the RGB LED will show the color blue for 5 seconds, meaning it's preparing for next round.

Step 1: Equipments

Step 2: Cutting Cardboards

  1. one 16 x 36 cm with two 1x18breach (back)
  2. two 16x36cm each with one 1x18 and 1x9cm breach(sides)
  3. one 18x14 cm cardboard with 8 x 4.5 breach (front)
  4. four 8x14 cm cardboard with 1 x 4 cm (top)
  5. one 12.5 x 10.5 cm (lower back)
  6. one 12.5 x 18.5 cm (upper back)

Outer layer

For the back and side shell, you need to cut one 16 x 36 cm with two 1x18breach(back) and two 16x36cm each with one 1x18 and 1x9cm breach(sides) For the front shell, you need to cut 1 18x14 cm cardboard with 8 x 4.5 breach. In order to increase the stability of the structure of the box, the cardboards have breach on them to cross through each other.

Top layer

For the top cardboard, you need to cut 4 8x14 cm cardboard with 1 x 4 cm breach. After constructing the top, the top will form a 3 by 3 grid.

The cover ( the one hiding the arduino nano and some battery c)

*The arduino nano and battery are glued on the back of the machine, therefore, the covers that cover the arduino nano and battery are technically the outermost.


The back one that covers the battery and arduino uno should be 12.5 x 10.5 cm and 12.5 x 18.5 cm since I left a space in between upper and lower cardboard. I left space because that one battery can open and close the Linear Solenoid Electromagnet. Normally when I am simply trying to test the function of codes I would close the Linear Solenoid Electromagnet because if LSE keeps running, it would slowly become hot and later broken.

Step 3: Fixing the Pencil Into the Grid

1. Upside down the machine and put the mechanical pencil from the bottom of the grid up to the top of the machine (in order to leave 0.7cm to put Linear Solenoid Electromagnet, put a 0.7 cm height small eraser at the bottom). The pencil is put in the middle of the 3 by 3 grid.

2. Making sure the mechanical pencil is fixed, you can pour the glue into the grid with a hot glue gun.

3. After waiting for a few more to let the glue dry and solidify, you can pull the pen lightly against the machine, testing if it is well glued in the middle grid. ( pull with harder strength after making sure it is already well glued.)

Step 4: Glue Mechanical Pencil Cap With LSE

Use a hot glue gun to glue the mechanical pencil cap with the copper-colored side of Linear Solenoid Electromagnet. When the LSE pushes the lead would fall out, when the LSE pulls the pencil lead would stop falling out. This needs to be well glued, or it would not function well.

Step 5: PIR Motion Sensor ＆RGB LED

*RGB LED, PIR motion sensor, Linear Solenoid Electromagnet, should all add extension cord since they have longer distance with the arduino nano and breadboard.

After making sure the LSE with the pencil cap, the PIR motion sensor, and RGB LED works, you can start fixing them on the machine. Stick PIR motion sensor at the grid that is closer to the front. The PIR motion sensor should face down. Thus, when people put their hands inside the machine, the combination of enclosed space (with one open front) and PIR Motion Sensor can better detect whether the hands are in the machine or not. On the other hand, in order for the users to see RGB LED, you can simply poke a hole at the front and put RGB LED inside it.

Step 6: Last “decoration”

Use the scissors to cut a little bit (shape like suare) at the top of the layer(cardboard), to form a ditch for the grove cables of RGB LED and PIR motion sensor. Since their location is closer to the front, they are too far away from arduino nano and breadboard, so they need extension of grove cables. In order to hide in the machine, I made a ditch to place them in. You can add a paper with a square in the middle to cover up the top of the machine, making the machine seems more neet. In addition, when the top of the machine is covered, there do not have any light inside the box expect the light leak from the front of the machine, increasing the stability of the PIR motion ssensor. At last, you can put two pieces of cardboards over the arduino nano and breadboard.

*the video is for the summary of last three steps.

Step 7: Code & Arduino

this is my code: https://create.arduino.cc/editor/chang_vanilla/94...

Relay module S connect to D2

PIR motion sensor OUT connect to D3.

PIR motion sensor VCC (5v) connect to arduino 5v.

PIR motion sensor GND connect to arduino 0v.

RGB LED red light connect to D4.

RGB LED GND connect to arduino 0v.

RGB LED greed light connect to D5.

RGB LED blue light connect to D6.

Linear Solenoid Electromagnet (which doesn't have difference between negative and positive pole), one connect to Relay module's com, one connect to battery's negative pole.

Battery's positive pole connect to Relay module's NC.

Step 8: Finish!