Creating a 3D printable 2- part mold which are separable for a curved shell My Question is about creating a 3D printable negative mold for an irregular concave mesh/object which has an outer convex and inner matching concave surface with irregular outline/edge.

I have made a mesh surface solidified (using knife tool, boolean modifiers, solidify) which will cover a curved defect on a model (like a lid).

I want a mold (negative)for this object which is


2 part and separable
Which can be 3D printed


I read multiple tutorials on creating a 2-part mold for objects most of those objects are convex on both sides. They work like charm for something object like "()" but not for something that is like "((".

I am having troubles to have matching concave surface in one mold and convex surface in another mold and both when put together we will have a space between then matching the object attached.

These molds need to be 3D printable.

I will attach the blend file and the outline of the png (drawing of how I want the mold to be).

Blender file for the object:(for which I want to make a mold)
https://blend-exchange.giantcowfilms.com/b/5572/

The outline image file for the mold:  (The red and blue are two parts of the mold and the while space is an empty space matching perfectly the object above)
https://ibb.co/yp5LjGJ
I posted this similar query in another forum and got some pointers and so I am sharing it here for the benefit of other users. You can read the entire post here but I am summarising it below.

I used the edge vertices to make a land area and then extruded in opposite direction to make a mold. For the other side, I first  extruded the edges in upward direction and then translated the entire mold by same units and repeated the same in other direction.

I am not sure if the final result is printable. But I got close to what I was trying to achieve.