I made this key housing for my 2006 Honda Civic after the casing broke. If you still have the metal key part and the circuit, then you can rebuild it. It may also work for keys from other Honda vehicles from the mid-2000s.
v2: I fixed an issue with the front (key-end) of the casing being too thick, which could prevent the removal of the key from the ignition.
v3: I fixed an issue where, by reversing the position of the electronic module, I made it difficult for the car's anti-theft system to read the chip inside. I flipped it back to the original, correct way.
If you don't have a 3D Printer, I also sell it on Shapeways: https://www.shapeways.com/product/UEJ4FX7SE/honda-civic-2006-key-housing
You will need:
2x M2 screws (6mm or 7mm long)
1x M2 nut
2x 4mm (OD) x 2mm (ID) metal washers (optional)
Use a power drill with a thin drill bit to clean out the holes before inserting the screws.