I recently ordered a MK42 clone from Orballo Printing at https://orballoprinting.com and the bed did not include the Led or resistor for the setup.I understand that future shipments will include the resistor and led.
If you’re not familiar with the led and resistor needed (optional) I’ve sourced them both over at https://www.mouser.com.
It’s a good idea to install 2 led’s that way if you get the polarity wrong your led’s will still work, or at least one of them will.
You really only need 1 resistor and 2 led’s, but keep in mind these are surface mount and are really tiny and subject to vanishing right before your eyes, so order a couple spares just in case.
Photos below followed by part number and direct link to each.
MK24 Clone from Orballo LINK
Now, although the video below will show a newbie how and where to solder the resistor and LED, keep in mind the board is not a MK42, but the video does a good job showing where and why.
That’s about it. Make sure to have your smallest soldering iron tip on, or maybe some solder paste and a heat gun.