Secret Safe

The Secret Safe is a secure device that contains a hidden compartment within it to keep items even more secure. The main compartment opens with a code input using a push button and a series of long and short pushes. Utilizing a photoresistor, the hidden compartment only releases once the sensor is covered and the input button is pressed again. The doors are secured by servo motors which turn to prevent the drawers from sliding open.

8.5”x11” 22pt Cardstock - 5

5” x 7” x 1/16” Cardboard - 3

2 Part Epoxy Envelope - 2

Photoresistor - 1

Servo Motor - 2

Push Button - 2

LED (Red, Green) - 1, 1

Resistors (220, 1000, and 2200 Ohms) - 2, 2, 1

3 Wire Extender - 1

3-Pin Header M-M - 3

Arduino Uno - 1

Breadboard - 1

4 AA Battery Holder - 1

AA Battery - 4

Wire Kit - 1

USB Cable A to B - 1

Packing Tape - 1

The Secret Safe is a secure device that contains a hidden compartment within it to keep items even more secure. The main compartment opens with a code input using a push button and a series of long and short pushes. Utilizing a photoresistor, the hidden compartment only releases once the sensor is covered and the input button is pressed again. The doors are secured by servo motors which turn to prevent the drawers from sliding open. When designing the Secret Safe, I had to consider the limitations of the tools on hand and how I wanted to prioritize functionality compared to my ambition for the project. This project was not my original idea for my individual projects but I ran into issues with the functionality that forced me to drop that project. I used a photoresistor as the hidden compartment sensor as it is small, discrete, and offers a quiet method to release the hidden compartment. A recommendation for someone attempting to replicate the project would be to ensure the strength of connections and the distances of the components. In my experience, a minor extension can cause the drawers to get stuck when pulling them in and out. If I had to do this project again, I would use a stronger material for the structure as I would hope to have the CAD skills to laser cut acrylic for the structure. I would also ensure that the mechanism is more secure as well as make the overall design cleaner. Lastly, I would use a numeric code entry instead of the button press entry. With more resources, I would continue to build on the structure, making it larger and using better joining methods for the panels. I would use 3D printed parts to offer the best security I can as well as rails for the drawers so that they slide effortlessly. 

The Assembly for the Secret Safe requires 3 sub-assemblies and then the attachment of electronics. The assumption that the breadboard/Arduino circuitry is made separately by following the circuit diagram located in Appendix B. The following images referenced are all found in Appendix C. Attachments can be completed by any sufficient adhesive method. Epoxy is recommended however, substitutes like packing tape are sufficient. All measurements are in inches unless otherwise specified. All dimensions are listed by horizontal length by vertical height when looked at flat from a top view and are orientated as such.

Cut the 22 pt cardstock into the following dimensions and pieces:

1. Two 8.5 x 6 pieces (Top and Base)
2. Two 6 x 5 pieces (Left and Right)
3. One 8.5 x 5 piece (Rear)
4. One 7 x 4 piece (Support)

Note: The lateral sides of the main structure will be slotted into each other before the top and base plates are attached. 

1. Take the 8.5 x 5 piece and cut two slots starting 0.5 inches from the left and right edge (The 5 inch length edges), opening to the bottom which are as wide as the 22pt cardstock and 2.5 inches long. These rectangular slots should be parallel to the 5 inch edge.
2. In each 6 x 5 piece, cut a slot of the same dimensions, one 0.5 inches from the right edge and the other 0.5 inches from the left edge. These rectangular slots should be parallel to the 5 inch edge.
3. In the 6 x 5 piece with a slot on the right side, create a hole in the top right corner centered 1 inch from the right edge and 0.5 inches from the top edge. The hole should be roughly 0.5 inches tall and 0.25 inches wide. This will be used to feed the electronics through later as seen in (1)(v).
4. In the 5 x 8.5 piece, create a hole 0.5 inches from the bottom edge and 1 inch from the left edge that is 0.25 inches in diameter. This will be used for the photoresistor. 
5. Line up the slots of the rear 5 x 8.5 panel perpendicular to the slots of the 6 x 5 panel slots and feed them through. Ensure that the photoresistor hole is in the bottom left corner of the rear panel and the wire hole is on the top right corner of the right panel. They should fit such that it stands flat but some adjustments are likely to be necessary. Use epoxy to secure the connections.
6. Center one of the 6 x 8.5 panels underneath the slotted assembly and attach it using epoxy for the base.
7. Repeat the same process with the last 6 x 8.5 panel on the other side for the top panel. The structure should look like (1)(iv) without the center support.
8. The final step is to attach the 7 x 4 hidden drawer support within the assembly. The support should be horizontal within the structure with 0.5 inches spacing between the front opening and rear panel, 2 inches down from the top of the main structure, parallel to the top and base panels. This will allow the hidden drawer to be pulled out and the wires to feed out the right panel. It is recommended to use the small drawer assembly as a spacer and turn the structure upside when proceeding with this step. Tape is recommended on the top as it will allow the drawer to move more smoothly.

1. Cut the 22pt cardstock into the following pieces:
2. One 7 x 1.5 piece (Front)
3. Two 5 x 1.5 pieces (Left and Right)
4. One 2 x 1.25 piece (For Locking)
5. One 0.5 x 1.25 piece (For Locking Support)
6. The 7 x 5 x 1/16 cardboard will be the base of the drawer.
7. The 7 x 1.5 piece should be attached perpendicular to the base along the 7 inch edge of the base with both 5 x 1.5 pieces perpendicular to both of those along the 5 inch edge of the base. All edges should be firmly attached to any other touching edge. Reference (3) in the Appendix.

Note: If looking from the top view of the drawer onto the base, with the front panel coming out of the plane at the bottom of base, the locking structure should be assembled in the bottom right corner as shown in (3)(i). 

1. The 2 x 1.25 inch locking piece should be parallel to the front panel, 1.25 inches from the front panel and flush with the right edge. The 0.5 x 1.25 should provide support for the 2 x 1.25 piece by attaching to both panels.
2. Tape is recommended on the top of the bordering edges as it will allow the drawer to move more smoothly.

1. Cut the 22pt cardstock into the following pieces:
2. One 8.5 x 5 piece (Front)
3. Two 5 x 2 pieces (Left and Right)
4. One 3 x 1.5 piece (Supports)
5. One 2.5 x 1.75 piece (Locking)
6. The 7 x 5 x 1/16 cardboard will be the base of the drawer.
7. The 8 x 5 piece should be attached perpendicular to the base along the 7 inch edge of the base. The base should be centered within the front panel. Both 5 x 1.5 pieces perpendicular to both of those along the 5 inch edge of the base. All edges should be firmly attached to any other touching edge. 
8. Cut the 3 x 1.5 piece along its diagonal to get two triangular pieces that will act as supports for the front panel. These should be attached to both the base and front panels 1.75 inches from each of the 5 inch long edges of the base.

Note: If looking from the top view of the drawer onto the base, with the front panel coming out of the plane at the bottom of base, the locking structure should be assembled in the bottom right corner as shown in (2)(i).

1. The 2.5 x 1.75 inch locking piece should be parallel to the front panel, 0.75 inches from the front panel and flush with the right edge and the right triangular support. 

1. Electronics Attachment
2. Connect the photoresistor to the 3 wire extender and feed the extender through the breadboard on the right side of the main structure towards the breadboard. The photoresistor should tightly fit in the 0.25 inch diameter hole on the bottom left of the back panel.
3. Similarly, feed the both motor wires through the same hole
4. Attach the hidden compartment servo motor to the underside of top panel, flush to the right wall with motor head away from the wall
5. Attach the hidden compartment servo motor to the underside of drawer support panel, flush to the right wall with motor head away from the wall 
6. As shown in (1)(v), 3 triple wire extenders should feed out the main structure to the breadboard assembly shown in (4)(i)

The circuit should be assembled as shown in the diagram. The commented code for the Arduino is also attached.

In order to operate the Secret Safe, one needs to know the combination to unlock it which is a series of short and long presses of the input button. With each press of the input button, the green light will flash as feedback to the user that an input was received. If the incorrect code is inputted when the unlock button is pressed, the red light will flash repeatedly. Once the correct code is inputted, the green light will flash repeatedly and turn the main door servo to unlock the main compartment. If the main compartment is unlocked and the photoresistor is covered and the input button is pressed again, it will unlock the hidden compartment by turning the servo motor. If the lock button is pressed, all doors will lock and the system will reset.