Electrically lockable treasure chest

In this project I built a treasure chest, which is mechanically locked by bars. Theese bars can be unlocked if you enter the right code. The code is entered at the rotable mouthpiece. The rotation is recognised by a rotary encoder. If the user applies the right code, the bars will open by the force of a servo motor. I thought that it would be nice if you had an extra feature by applying the right code, so I planned a lifting device which opens the chest up to nearly 70 degrees. This opening process will is initialiesed by a stepper motor. In the inside of the chest, are two small areas, where you can store something. To get a better sight, I installed some leds, which activate when the chest opens. To close the box you have to push down the top of the chest to assure that the bars dont hit any obstacles. To confirm the closing procedure you have to push the rotaryencoder button for a short timeperiode. 

For this project I used some step up- and downconverters to supply the boards with power. The whole project is supplied by 4 pieces of 9V batteries in parallel. The steppermotor is driven by a driverboard. The leds and the 7segment display is driven by two attinys 2313 und the main brain of the project is an arduino nano. 

All of the used parts of the chest were planned in fusion 360 and printed in PLA with my Prusa. To hold the pieces together I used some threaded inserts (m3/4).