If I'm being honest I could have documented this project better with more pictures, but I'll try to describe the process in enough detail to re-create it below.

Steps in order—​​​

• first drew the outline of the sign on the door and planned out how each strip of neon would look, I used pencil for the outline and sharpie in the corners, I did some measuring but mostly eye-balled it 

• then, I basically took the double-sided tape and peeled only one side and stuck it to the door in the shape I wanted, I tried to make the pieces as continuous as possible, with no overlap, for SUPER sharp corners I didn't place tape down, I only secured the straight edges going into and out of the corner with the intent that the LED strip would naturally form a curve in the corners—forcing the curve just increases the chance of it ripping off the tape when we attach the strip to the door 

• I drilled some holes in the door near where the "end" of each LED strip would go, I tried to do each color continuously so I could use the ends to power them, doing multiple strips of each color would mean I'd need to add wire between each of the strips to power them, this way I could pass just the end of the wire through the door and hooked the three strips up to each other. In hindsight, I should have done the drilling before the tape because some of the door fragments got stuck on the side of the tape since I used thick double-sided tape, and I had to spend some time brushing it off—but not a huge deal

• I slowly peeled away the second layer of double sided tape, I exposed all of the sticky side that corresponded to each strip of LEDs before I laid them on. I slowly laid the LEDs onto the strip, pressing into the tape to get as good adhesion as possible. I fed the exposed wires through the holes

• some tight corners of the LED strips weren't being held down well enough by the double sided tape, some curves were hard to get with tape, and I wanted to secure the wires and hide the holes in the door a little better, for all of this I used hot glue. Potting the holes, and then using small dabs of hot glue to hold the strip to the door in certain locations

• on the back side, I wired all the LED strips in parallel, these LED strips have their own internal current-control drivers so you don't blow the LEDs by passing too much current (these strings accept a voltage input, some accept a current input, be very careful when buying a strip to check which one it takes)

• just cleaned the wires up a bit and then plugged in the power supply to the wall! Only thing here was to make sure the wires and the power supply don't prevent the door from opening and closing.