This is a remix suggested by Azurewren based off of the octopedes from McGybeer and Ellindsey.
I would recommend to scale the .stl to ~150% which worked best for me thus far. Tho keep in mind that:
a) for the head you'll need support, for the tentacles not necessarily (however if you print them with support the removal takes usually more than an hour)
b) I could'nt get the bottom perfectly flat, if you scale it up, take a look at the first few layers
If the model looks weird in the preview try "Union Overlapping Meshes" in Mesh Fixes in Cura.
If you have trouble with bed adhesion for the tentacles you can use a brim (which really helped my little octopus)
@150% scaled the print took my Prusa i3 Mk2 roughly 7h (with supports and brim enabled)
The easiest way to remove the support for the tentacles is by using the "Support Blocker" in Cura. If you find a better way let me know :)