Inspired by the Black Ghosts from the series Ajin, I've made my own ghost:)
In order to align the parts, I've left a slot that accepts 1.75mm filament. The slot is 2mm, but you may need to open it up using heat or a file. It can close up do to first layer flattening.
The files include built-in Meshmixer supports. I've also included the full model if you want to do it yourself.