This Instructable will show you how to make a fully 3D printed "Whiskey and Coke" RFID Lock Box.
Step 1: Intro
Over the last few years, my family has made it a tradition to go to a different puzzle room in the city every Christmas. Despite rarely getting out of the room in time, they are always challenging and fun. I couldn't help but wonder how they make all of the different puzzles and in this project I will show you how to make an RFID lock box similar to one that I saw in a puzzle room. It seems that in many of the puzzle rooms I have been in, they have used an RFID chip hidden in something which then needs to be placed in a certain location to activate a secret door or open a box. This instructable will teach you how to make a generic box that you can add the specific puzzle to later on. I chose to add a Coca-Cola symbol and hide the RFID chip underneath a Jack Daniel's mini-bottle, hence the whiskey and coke combination. The entire box design will be done in Fusion 360 and 3D printed in PLA. I saw the Safe and Secure contest going on and since this box could easily be used to store valuables I decided to enter it.
Step 2: Components Needed
For this project, the following will be needed:
- Arduino Nano with USB cable
- On/Off Switch
- 9V Battery or 5V Power Supply
- 2 SG90 Servos
- RC522 RFID Module
- At least 2 RFID tags
- Soldering iron and supplies
The Arduino Nano is a microcontroller board that is based on the ATmega328. It has similar functionality as an Arduino Uno but has a tiny footprint (18 x 45 mm) which makes it great for projects that need to be smaller in size like my RFID lock box.
For the RFID functionality I will be using an MF RC522 which is a highly integrated read and write card chip applied to the 13.56 MHz contactless communication. It is a low voltage, low-cost ($1.6 on AliExpress), and small sized non-contact card chip. I will be using a few RFID tags to control the locking/unlocking mechanism of the box.
Step 3: Electronics
Now that you have all of the required components, it is time to start working on the electronics. I would recommend first building the circuit on a breadboard, programming the Arduino Nano using the Arduino IDE (will be explained later), and then once everything is functioning correctly solder everything together on a perf board.
The Arduino Nano can be powered from the USB port during testing so the 9V battery and SW1 will not be needed until final installation in the enclosure. The SG90 servos technically need more power than you are likely to get from the onboard 5V regulator or over USB, but I have found the box to still function correctly. Later on you could always upgrade to a better battery source or if you were okay with having a external power supply that would be the preferred method to power the lock box.
The LED's are optional but may prove useful during testing of your lock box.
Step 4: Programming the Arduino
In order to control access to the box, we need to program the Arduino Uno. I modified the Access Control example that comes with the Arduino library that you will need to install from here.
After installing the library (there are many tutorials of how to do so online), you will need to upload the code I created that is attached.
Step 5: RFID Chip Control
After the code is uploaded, we will need need to test it using our two RFID chips.
Immediately after uploading the code click to go into the serial monitor in the Arduino IDE.
Scan the RFID card that you want to be the Master Card (Always will open box and able to add additional RFID cards).
Then scan the RFID chip that you will be using to unlock the box. The card will be written to the EEPROM to store the data even if power is cycled.
Then scan the Master RFID card again, this will lock the box.
Step 6: 3D Design and Print
Now that we have a working prototype of the electronics and programmed the Arduino Nano, we can start to work on the design and printing of the enclosure and lid. Luckily, I did the hard work for you all and have uploaded my designs on Thingiverse here for everyone to download. If you chose to make your box the same as mine with a Whiskey and Coke combination, the coca-cola symbol can be found on Thingiverse here.
Step 7: Install Components
In this step, I will walk you through how to install the components and solder everything together on a prototype board. If your breadboard is small enough to fit in the enclosure, then the prototype board is optional but the wires will obviously not be as secure.
Steps to Assemble:
1. Remove supports from 3D print
2. Insert the SG90 servos into the slots. Insert the three pin wire connector from the servo through the bottom and press fit the servo into the slot. It should be very tight and difficult to remove.
3. Insert the RC522 RFID module into the middle location. It should snap right into the middle and not move around easily.
4. Place the rest of the electronics into the box. I used some velcro to keep them attached.
Step 8: RFID Chip Removal
Depending on what item you chose to make to unlock your box it might be helpful to remove it from its keychain prison. I used a pocket knife to cut around the edges and then pop one open like the picture above. I then used the knife to carefully remove it from the glue so it was just the rfid component. I then was able to easily tape it to the bottom of my mini jack daniels bottle. Epoxy could also be used to attach it but since I might be changing my unlock item later on so I figured I would just use tape for now.
Step 9: Try Out the Box!
At the start of the video I demo the box opening by putting the Jack Daniels mini-bottle on top. Note: If you want the box to lock on startup you will need to change the servos start positions in the code. I will let you figure that out.
Thanks for reading!
Runner Up in the
Safe and Secure Challenge