This video will show you how to create your own LEGO bricks that enclose other LEGO bricks. I used the polyester resin pouring method to create the brick by utilising a silicon based mould. These step by step instructions help you to create your own LEGO brick. This is an ideal present for all your AFOL friends.
Here are some more photos of the models I made:
2 thoughts on “LEGO Resin Casting Brick in a Brick”
I work in a company where electronic components  are cast. We always degas the resin before casting. Obviously, you also know about this necessity because you did this before casting the figure but surprisingly not with the Duplo. In my experience, this would mitigate the risk of moving and floating for the piece. Is there a reason you did not do so?
 examples: https://commons.wikimedia.org/wiki/File:Wiki-Folkos-P1090317-1.jpg
The problem with the Duplo bricks was that they have large cavities in which air is trapped. It is not the pink material that has all the air. A solution would be to use a filler material to close the inside of the Duplo brick.