I’m new to the forums here and would like to share something with you all. I have been reading around the forums and I have seen a lot of requests for customizing FL’s GUI. I know the dev’s have mentions a few times that currently it is not really, or *easily able to be done. That part is true
however I have been looking into FL over the past few days and weeks to see what I could accomplish. So far I have been able to access most of the areas of FL except for a few which I am still testing such as the volume meters, step blocks and a few others. Those are quite tricky to work with for me. I would also like to say a few friends of mine have been doing all of this as well and they are making amazing progress. So they deserve a round of applause! 
Anyways, to get to the point. I would like to share my process with anyone here who is curious how this is done. Hopefully I can explain in a way most of you will understand. So...
Here is my FL skin for the most recent Fl update. The programs I use are resource hacker, notepad, diffmerge and still testing with a debugger x64dbg(super messy to work with and would love to see if Shinyless or anyone can comment maybe on how to more easily locate sections and change values) . When you use resource hacker you locate FLEngine.dll and open it up and in there is a folder that has most of the areas in FL you are able to modify. *Warning- unless you know what you are doing, a single misplaced value could corrupt your .dll* from there it’s using a color value converter like colormania to replace the default values with your custom color.
I will go into further detail tomorrow if anyone is interested and brave enough to try it out so please give me your thoughts if you guys want me to draft something up. Hope this gets people excited!!