Saving a snapshot rendered object's sprite

How do I…

Since you can’t use the event sheet actions to open “save file dialog”, is there a way using javascript to achieve it?
Bascially, I want to make a character creator where there would be a layer where all the character parts are present. When clicking the save button after you finish making the character, an off screen object will be rendered to the layer using the Snapshot extension and then it will make you able to save the character you made.

What is the expected result

Being able to save/ download an image of the render object sprite.

Related screenshots

Concept of how it will work/ look.