So I've been looking around a little and figured out how to reprogram those 4 extra keys on a Ducky keyboard.
You need to download a little tool called AutoHotkey, which can be found here:
https://www.autohotkey.com
During the installation, make sure you enable the drag and drop feature to make it really easy. Especially if you are not familiar with making scripts, just like me. You might also want to choose UNICODE over ANSI during the installation, as it supports more languages/alphabets.
Once all that is done, you'll be able to make a script for this program. This is done by: right click on your desktop -> New -> AutoHotkey Script.
Give it a name of your choosing and afterwards right click and select edit script. Now copy paste one, or all, of these functions inside it and save the file:
Code:
SC121::Media_Stop
sc16b::Media_Prev
sc16c::Media_Play_Pause
sc132::Media_Next
Double click the file, or right click it and select run script. Try it out on whatever media player you have to see if it worked.
Here you can see what each of these "SC" keys represent:
Code:
SC121 = Calcalutor Key
sc16b = PC Key
sc16c = E-mail Key
sc132 = Home Key
The sources to where I found all of this can be visited here:
https://linustechtips.com/main/topic/80818-ducky-shine-3-keyboards/
https://autohotkey.com/docs/Tutorial.htm
You should also be able to do this by creating the right registry files and save it in there, but I am not too sure how that works (yet), or if there are any major differences etc.
Looks like all you need to do now is finding that 1 keycap to replace it with =)