Here is a couple of two little ghosts, resulting from a 3D tutorial I created (but in french). The goal is to put in the body LED lights, like candle types or the disc type that you can put in a closet.
Here is a short movie with the candle type LED: https://www.youtube.com/watch?v=wVFC0BEGQdo
PLEASE READ THE INSTRUCTIONS BELOW!!
As you will notice, the modes are not hollowed. Your slicer will do it for you! You simply need to move your model around 3mm down the 0 of the Z axis (below the grid) and be sure that you have zero bottom solid layers. It works perfectly with Cura and Simplify3D. When you produce the GCode preview, double check that the bottom is fully open.
Also use 2 outlines (0.8mm). The model can be printed with only one outline, but it's not advised. The model doesn't need support (and infill of course!), however I suggest to print at a lower speed than usual (no more than 50mms/). It is important to have a nice surface.
Don't forget to add a skirt connected to the model to be sure your model will stick well to the build platform.
The Candle LED I'm using (charge them through USB!) https://amzn.to/2CIh75n
The Closet type LED, with a remote control and timer, perfect for night lights for kids: https://amzn.to/2pRJAxa
Here is a link to the tutorial, however it is only in french. Perhaps you can try the YouTube auto translation tools for the subtitles?