Did you know? LEGO Bricks are made to highly precise tolerances. Modern LEGO bricks still fit perfectly with bricks which are decades old.
Create the 2×4 LEGO Brick as shown:
Set the physical material of your brick to ABS plastic. This is what LEGOs are made of. You should get 2.27 g using the diagram above, with a tolerance allowance of 1g.
If you would like to tackle this using parametric design (more challenging), you can use this tutorial: https://www.instructables.com/Parametric-Lego-Bricks-in-Fusion-360/