Got a question about Dragons & Half-dragons

Ok i know there is a template to make a half dragon, but thats only for the like 8 dragons they have listed, how could u make a half dragon from another type of dragon, i know there r some other ones and also homebrewed ones,

By changing the breath weapon, and immunity to be the same as the breath weapon. There's not really much difference among the dragons.

the Draconomicon goes through almost all of the other dragons. The OA (Lung) dragons are different though, since the don't have standard breath weapons or elemental immunities (usually) ...

if you follow domino's suggestion you'll get just about every other dragon type out there. If a dragon has more than one resistance only pick one (same for breath weapons).

if a dragon doesn't have those you might want to give them some other ability ... swim speed, waterbreathing or ability hold breath underwater for hours instead of minutes ...

if it doesn't have any of those, then just don't give it (the Half-Yu Lung/carp dragon's only special ability is waterbreathing ... no immunity, no breath weapon)

You can also add twists to throw a wrench in the works. Dragon Mag has a listing for Half-Shadow dragons from a specific drow family. Drow/Half-Shadow dragons from that family have wings if they are Medium sized, as opposed to Large.