Airpak - Mirroring non-uniform blocks in the height direction
The mirror utility does not work in the height direction for non-uniform polygon blocks.
This solution is an easy workaround.
* Copy the non-uniform block in its own position (no mirror, no rotate, no translate).
* Reverse the extrusion of the new block by changing the sign of the height for the block.
* Move the new block by a distance equivalent to twice the height of the non-uniform polygon block.