When the gadget has both a laser and a flashlight, clicking the regular "Customize Gadget" button will show you this dialogue box first:

You can choose which sub-gadget (laser or flashlight) to customize, or you can use the default ui.

This is what the modded colorpicker customization ui looks like:

You can click and drag on the hue slider, and anywhere on the "gamut box" (the big colorful square), to select the color from that point.

Q: I'm crashing when I install this mod!
A: Check your crashlog. If it indicates that you don't have Color Picker installed, then go install that.

Q: I'm crashing when I install this mod and I'm sure that I have Color Picker installed!
A: Post your crash log in the comments.

Q: Why do I have to install two mods just for this?
A: The color picker UI library I wrote is used by at least two of my other mods, and I could bundle a copy of it into each one, but every time I push an update to it, I don't want to do the same for three or more separate mods that each have a copy of it inside. That makes the process very time-consuming, and I'd rather use that time for other things, like making more PAYDAY 2 mods, and pondering the meaning of life.

• The color preview in the blackmarket ui does not immediately update with your chosen color. This is purely a cosmetic issue; your changes will still be applied properly to the gadget.
• You only have the option to use the vanilla customization ui if you are customizing a gadget that has both a laser and a flashlight, eg. the Combined Module, Military Laser Module, or LED Combo. This is because I think it's annoying to have to navigate through an extra dialogue box every time you want to customize a gadget when you don't actually need to.