yes. Something easy to remove to reduce the silicone volume and thus creating space to flex the silicone away from the casts surface once cured.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

You would need a multi-part mould.  for the inside, you would us a filler that can be removed from the silicone after curing.  You can then remove the filler and flex the silicone off the master and any subsequent parts you make.  

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Good day, 
I hope you all are well. I am very new to mould making and am having a challenge. I want to make a silicone mould of a vase that is not straight up and down, it has curves and is hollow inside. I have done some research and seen how someone made a mould of a solid ball in two parts. I have been trying to wrap my head around how I would get this done for a vase with a hollow section bue have not come up with anything that looks practical. I a seeking your guidance, thanks in advance. I have attached two vases I am attempting to make a silicone mould from.