If you want to put the texture onto your nails, only need the HUD, but if you want sell appliers, then you must make too a prim and put into the script: LucyBodyNailsApplierGreen.
IMPORTANT:Your prim for sell appliers must be colorized green 00ff00 to only receive data, after this you can change white, then is locked to changes.
Drag and Drop a texture from your Inventory into the red bottle of the HUD. Press button APPLY, then the textures data are sent to your prim applier and the button RESEND.
The button RESEND is only for apply to your nails. Is not a need to use if you are making your applier in a item made by you.
The first step is to make the texture using as template the UV map of one texture for nails.
You can make a texture as this:
Note that the lines must be layer of Photoshop as template, and these lines between means all the sizes that get the nails.