The idea is to make an inexpensive target which will increase shooting accuracy and speed.

I used two coffee cups as the enclosure.

The project cost around $27.00 including the two cups of coffee.

Using a 5 volt Trinket Pro from Adafruit in place of the Teensy 2.0 would get you under $20.00

Step 1: Gather Your Parts and Tools

Parts List:

1 1” Photoresistor PVC-PEC-1.0 — $1.35
1 CET12A3.5 13 352 Piezo Electric Buzzer - $1.95
4 3mm Red LEDs $0.05
1 3mm Green LED $0.05
4 1K resistors (for Red LEDs) $0.01
2 10K resistors (for Green LED and Photresistor) $0.01
1 Teensy 2.0 (any 5v Arduino compatible board) $16.00
2 paper coffee cups $1.65
1 Pocket Juice Portable Charger 2000 mAh $3.50
Hookup wire (I used 24 gauge) $0.02

Tools:

knife
wire cutter
soldering iron
hot glue gun

The hardest part to find was the one-inch photocell. I purchased ten of these from Surplus Sales of Nebraska, 1218 Nicolas Street, Omaha Nebraska through their Internet site. I think everything else was available at Amazon, Adafruit, or Sparkfun. I had several Teensy 2.0 Arduino boards available, so I used one in this project; however, you could save about $7.00 by using a 5 volt Trinket Pro board from Adafruit instead.

I built a pistol which would fire a laser burst, and then I found the LaserLyte Trigger Tyme Pistol Trainer LT-TT for around $35.00 without the laser and modified it to fire a laser burst (maybe a future Instructable). You can purchase the LaserLyte pistol with their laser system for around $100.00.

Step 2: Cut the Cups

The first step is to cut the cups.

So I didn't have to solder these small parts inside the tight space of a coffee cup, I cut the bottom out of one cup, cut off the bottom-one-inch of the other cup, and placed the false bottom into the first cup. (Wow, that is a confusing sentence.)

I have included a quick video showing what I mean.

Step 3: Place Your Parts

Next I placed the parts by pressing each through the false-bottom.

I placed the four red LEDs on one side with all of the negative leads toward the outside edge of the cup.

I placed the green LED on the opposite side with the negative lead toward the outside edge of the cup.

I placed the photocell in the center with the pins facing the two other sides. Don't worry about reversing these leads, polarity does not matter for the photocell.

(If your LEDs have two legs of different length, the longer one is positive. If they are the same length, the LED should have a flat area on the plastic housing, the lead adjacent to the flat area is the negative lead.)

Step 4: Hot Glue

Next, I hot glued all of the parts in place.

Step 5: The Hook-Up

Prewire the Microcontroller Board

Start by cutting ten 5-inch lengths of hook-up wire. Strip the ends and solder one end of each to the following pins on the Teensy 2.0 board.

GND
+5V
Pin 21(A0)
Pin 8
Pin 9
Pin 11(A10)
Pin 12(A9)
Pin 13(A8)
Pin 14(A7)

Connect the Common Ground Wire

Next run a wire along the side of the false-bottom (this is silver in the picture). Each negative-lead of the 5 LEDs connects to this wire.

Connect the Buzzer

When you prewired the micro controller board, you used 9 of the 10 hookup-wires. Using the remaining wire, solder the negative lead of the buzzer to the common ground. Now solder the negative lead to the wire you connected to the GND pin of the micro controller board (yes, this puts two wires to the negative lead). Solder the positive lead of the buzzer to the wire you connected to Pin 14.

Attach the Resisters

Solder one end of each 1K resistor to each of the red LED's positive leads. Solder one end of a 10K resistor to the Green LED's positive lead. Solder the other 10K resistor so one end goes to the common ground and the other goes to one of the photoresister's leads. (Again a picture is worth a 1,000 words, so I hope the photo helps.)

Final Hook-Up

Connect your prewired pins as follows:

+5V -- To the photocell lead which has not been connected yet.
Pin 21(A0) -- To the photocell lead which you have already connected to ground via a 10K resister.
Pin 8 -- To the resister on the Red LED you want to light when 5 points have been scored.
Pin 9 -- To the resister on the Red LED you want to light when 10 points have been scored.
Pin 11(A10) -- To the resister on the Red LED you want to light when 20 points have been scored.
Pin 12(A9) -- To the resister on the Green LED
Pin 13(A8) -- To the resister on the Red LED you want to light when 15 points have been scored.
Pin 14(A7) -- You should have already connected this to the positive lead of the buzzer

If you mix up your pin numbers on the LEDs, you can just change the numbers in the program. (I did, and that's why they don't go in order above. Oh well.)

Step 6: Final Assembly and Programming

Hot-glue the buzzer to the surface of the false bottom, then insert the false bottom into the other cup and glue it in place.

Here is a copy of the Arduino Code. Load this onto the micro controller and power it with the rechargeable battery using a USB cable.

I hot-glued the battery inside the cup as ballast which puts my score-counting LEDs on one side and the green LED on the other.

The software is designed to give you around two seconds to draw and fire. Five consecutive hits will cause one of the red LEDs to light, five more will light the second, etc. up to twenty. A miss will cause you to lose all of your lights. You can play around with the software to give yourself more time, change the tune, or change the rules all together. I hope you enjoy this inexpensive little project.