I would still make a full size model with temporary connections. When it comes to sensors and long wire lengths, you may need to tweak parts and code to accommodate the effects.
Then once it actually is working, solder connections that likely won’t need disconnecting. I like screw terminals for connecting bare wire.
The point of a development board like the Arduino is technically to make an end product just using the ATMega328 alone on a pcb with just the needed pins broken out, so keeping the dev board in the end product is like using hardwiring a multimeter to a circuit.
Not a problem, though, lots of people buy a smaller version like the Nano from the Uno. I move a lot of simple projects such as yours to an ATTiny85 using a dip socket on soldered perf board cut to size.
The header sockets and using jumper wires are not for long term use, they’ll work until they don’t. Seems a waste if it’s your only Arduino that you can’t keep learning/devving with it if it’s sitting by your stairs.
Thank you very much for your reply. Honestly, since this is my first project, a lot of the terms you used were way above my head. However, I am willing to research and learn.
Since I have never worked with programmable boards before, I chose Arduino Uno primarily because it seemed easy to work with, had plenty of pins and USB connection. Can I simply swap it with Arduino Nano (http://amzn.eu/673bnoY) or will I need to change the code? My project requires 4 data pins (1 for LEDs, 1 for LDR, and 2 for PIRs).
Lastly, you mentioned that long wires may require additional/modification to components. Would you be able to elaborate on this a bit? One of my PIRs and the LDR Sensor will each be around 3m away from the Adruino board. Both of these sensors are on their own board (with potentiometers etc). Everything will be powered by single 8a 5v power supply.
(I like the idea of screw terminals, Thanks.)