I would be careful with resin as filler material, 2 component epoxy for example gets really hot due to the polymerization process (around 70-90°C in some cases) and could deform a PLA shell easily just because of the heat. They also suffer a lot from shrinkage, wich might be problematic too.
Maybe, as already mentioned in this thread, concrete would be a safer bet.
I would be careful with resin as filler material, 2 component epoxy for example gets really hot due to the polymerization process (around 70-90°C in some cases) and could deform a PLA shell easily just because of the heat. They also suffer a lot from shrinkage, wich might be problematic too.
Maybe, as already mentioned in this thread, concrete would be a safer bet.