I made this box to house a 1602 LCD and an Arduino Nano, an LM2596 DC-DC converter, and a relay. I have it hooked up to my garage door and it will display:

THE GARAGE DOOR IS < OPEN >

        OR

THE GARAGE DOOR IS CLOSED

If pin 8 goes high or low. schematics and sketch is included.

I modified the sketch so I could mount the Nano right to the LCD with pin headers.

• LCD RS pin 4 to Nano pin 12
• LCD E pin 6 to Nano pin 10
• LCD D4 pin 11 to Nano pin 5
• LCD D5 pin 12 to Nano pin 4
• LCD D6 pin 13 to Nano pin 3
• LCD D7 pin 14 to Nano pin 2

As a matter of fact, everything mounts to the LCD. The nano hangs with headers. I made a +5v and -5V bus with some paper clips and the LM2596 hangs on those. For the relay I just put down a small blob of silicone.

If you print these with ABS do not print all 3 parts at the same time. They will sit on the bed too long and warp. Print one at a time. They will still warp, but a lot less.