These are simple decorations for Halloween. Print them out, and hang them up! You could hide sweets (candy) in them, or maybe use a LED tea-light.
The 'split' files are best for filament printing, the bat should be fine without any supports, the ghost works better with supports.
The 'whole' files will be better printed by professional sintering machines, or if you want to remix the design. The versions without the rings could also make good bowls for the table top.
Supports for the Ghost, none needed for the Bat
The 'split' versions need to be glued together. I used a gel based superglue, allowing for a little bit of repositionability! The Ghost version has a marker to make sure the two halves are aligned properly.