It's a floating red cross in a heart! 
 

I printed a previous version of this with less strings, and some design problems, so this is the second version. Improvements are very welcome! 

I printed this with a 0.2 mm nozzle, with Creality K1. 
Optimal profile ( it says 0.16 mm nozzle ) in orca slicer will make the strings too easy to break, so I suggest to use the standard profile. 
Beware: some strings might deform during bridging because of the cooler vents so I suggest turning it down. Although I haven't figured out the desired amount yet. 

In case the slicer makes unwanted bridges between the strings, try rotating the model a bit on the z axis.

Removing this from the plate makes good practice if someone aims to be a surgeon one day, but it can be managed. 

Good luck!