Cj:
The best thing I've found is to purchase something called a LACE FRONT wig.
As with most things, I've found that you won't be able to find something that will exactly match your needs... so without making it fully from scratch, you can find something close and modify it.
For my joker, I found a local beauty supply store and went in. I got a brown, curly, shoulder length wig and trimmed it myself.
In the Lace portion in the bangs of the wig, I then began to cut down all the hair I wanted to make it appear as though it was thinning.
By meticulously taking tweezers, and going through and removing the knots in the lace sporadically, it begins to make it look more like a blended- receding hairline.
For the green color, I was content with purchasing the neon green spray on hair color and lightly coating it on, and then running my fingers through it to mess it up and thin it out.
With further blending and tweezing, makeup helps complete the look.
NOW, that's what I did with mine, and I like it plenty!
I'm somewhat unhappy with it because I can't make it blend farther back into the head for the look that it is fully thinning because most lace-front wigs don't have THAT much lace to work with in the front before it turns into the wig-net.
If you have an extra 300 dollars to purchase a FULL LACE wig. Go for it, just don't mess up
Or, if you have the capacity, obviously the best route is to make, or have someone make a Full lace wig from scratch.