Trimming Resin

I bought a pair of replica walrus tusks for a skull that came without tusks. However, the replicas are too thick at the base to fit into the opening in the skull. I tried to thin them out using rubbing alcohol, sandpaper, and a dremel grinder. Rubbing alcohol did nothing, sandpaper and the dremel worked a little bit but only negligibly and I wore out three grinders barely putting a dent in it, not to mention the mess that it makes. I only need to take it down about 1/8” around the circumference of the base and taper it down about 3”, but nothing I’ve tried works in a practical sense.
Anyone have any methods or tips that could help? I don’t have much by way of powertools, and I live in an apartment so I don’t have like a tablesaw or anything. If there’s some kind of chemical solution rather than mechanical that is preferable, but I can figure something out either way.

 

So cut it on the inside rather than grinding it from the outside? Makes sense! Should I expect it to be flexible enough to not crack or split when squeezed? Would I have better results with a hacksaw or a regular wood saw?