making a connection on two molds (hard to explain in the title)

[carmiel]

i have a right and left sides of a mold and i need a way to change the mesh so that i can connect the two side after printing then and filling them.

thanks in advance

[Modron]

male / female interlocking ‘tabs’. something like this?:
( similar to a ‘mold key’ for making molds. )