As promised, here is a quick tutorial on making your own nail art decal. It is really easy and simple, however, there is quite a bit of wait time involved depending on the complexity of your design. It also takes at least 24 hours before your decals are dry completely so they will come off the plastic.
I place a cardboard inside a clean ziplock bag so the bag doesn’t wrinkle or move too much when I am painting my design.

I also draw a guide for my designs so I don’t make them so big that they don’t fit on the nail bed.

I use the brushes that comes with the polish for general design and a dotting tool for the fine details. The first layer of the polish should cover the entire design area so it can act as the base to keep the decal together. Once, you draw or outline the design, fill in the shape with a heavy coat of polish because it will be sturdier when dried. You will have to wait until the surface of the design is dry enough before you can add the second layer.
Since, I am making glow in the dark decals, I used the Disco Light transparent glitter polish as a second layer for my skulls and eyeballs.

Then, I use the larger dotting tip to make the eyes. Then, I used the finer dotting tip to draw the “mouths” of the skulls.

Here is the finished decals and I also made a little ghost for the pinky. Place the designs in a well ventilated but dry area (the garage is a great place) for at least 24 hours.

To peel the designs off the plastic, you need to removed the cardboard piece and bend the plastic slightly where the designs are located. A design that is dried properly will “pop-off” easily when the plastic bent. If you know the designs are dry but they are not coming off easily, use a pair of tweezers or tooth pick and carefully loosen the edge of the design. Then, peel the plastic away from the design, instead of peeling the design off the plastic.

To adhere the design to your nails, first paint the nails with the desired base color and let it dry for 15 minutes.
Then, apply a coat of clear topcoat and place the decal over the nail bed.
You will need to “form” the decal to your nail bed, as they can be quite thick. Lastly, apply at least one more layer of topcoat over everything.

A few more tips before I go, one, make multiple of everything because you will mess up or tear a few. Two, if the decal doesn’t come off easily the first time, let it dry for another 24 hours. Three, get a very thick top coat like Poshe or Vite Seche because it will really make your finished nail look glossy and smooth.
I hope you give this DIY nail decal a try!