When you say "custom folder art", are you referring to the box art folders, for specific consoles?

If so, then you don't want to place that in folder images. You'll want to go to you Hakchi2 software and click on tools and then select the "prepare art folders", in which you'll then need to select the specific console you want to set up art for. So for example, say you want to add box art for the Genesis. You'll want to pick that console and then click ok and Hakchi will create that folder for you. You'll then find that folder in your hakchi2 software directory, simply named "art". From there, you can drag and drop any box art or artwork in general to it and make sure they are properly named (basically copy and paste the name of the game, over to each corresponding artwork), to make it easier on you in the long run, when running a full quick scan for artwork, per game.

​

If I'm way off base here and this isn't what you're asking about, then my apologies. Hope you find the help you're looking for. :)