Im not sure I quite understand how it is i risk frying either if the led is rated 50ma but the ardiuno only provides 40ma. Does that not mean that only a max of 40ma will be going through the led? And a resistor would lower that 40ma even more? Please explain what I have wrong here, honestly my electronic knowledge is very bad as im better as a coder than electrician.
I am very much thinking about just going with it as its only a personal project and if anything does fry the parts to replace are cheap enough but i will then need to rethink my plan. Im kinda one those kinda people that plugs stuff in and hopes it doesnt blow up and if it does, dont do that again. Also the arduino will just be powered via standard usb cable too, nothing fancy. Plan b is to add the resistor and wire up multiple irs close to the devices like christmas lights that way it will definately work and be safe too.