Haha! No metallic kobolds, eh? Well, to sate the desires of my 
Exalted Deeds friends I feel obligated to post a metallic version your kobold.  Let's just say they hail from the upper planes, eh?
                
                It's somewhat more powerful because it's an outsider and because it isn't subject to light-blindness and has 
smite evil once a day. I'd suggest a +1 ECL over the regular kobold.
                
   The PrC has d8 HD and clerical abilities. I balance this by reducing the natural armor bonus by 1 at levels 2 and 4.
                
                Metallic Kobold
                Small Outsider (Good)
                 Size: Small (+1 attack, +1 AC, +4 Hide, -4 Grapple, 3/4 carrying capacity)
                 Speed: 30 ft.
                 -4 Str, +2 Dex
                 Darkvision 60 ft.
                 Natural Armor bonus +1
                
                
Racial Abilities:
                - Smite evil 1/day
                
 Draconic Heritage: Choose one metallic Dragon type, which is your ancestor. Your scales are tinged with this color, and you have Energy Resistance 5 against damage of this energy type:
                 - Gold: Fire
                 - Brass: Fire
                 - Bronze: Electricity
                 - Copper: Acid
                 - Silver: Cold
                 
    Skill Bonuses: +2 Climb, +2 Jump, +2 Move Silently, +2 Spot, +2 Search, +2 Craft (Trapmaking), +2 Profession (Miner)
                 
                 Favored Class: Cleric
                 
        Special: Metallic kobolds may take a 4-level Racial Prestige Class. (As a PrC, these levels cannot cause an XP penalty.)
                 
                 
                 
Metallic kobold PrC
                 HD: d8
                 BAB: Two-thirds (as Cleric)
                 Good Saves: Reflex, Will / Bad Save: Fortitude
                 Skill Points: 4 + Int bonus
 Class Skills: Balance (Dex), Climb (Str), Concentration (Con), Craft (Int), Hide (Dex), Jump (Str), Knowlege (any) (Int), Listen (Wis), Move Silently (Dex), Profession (Wis), Spellcraft (Int), Spot (Wis) and Swim (Str).
	
		Code:
	
	
		[u]Level 	BAB	 Fort	Ref	Will	Spellcasting		Special Abilities[/u]
 1	+0	+0	+2	+2     --			Energy Resistance 10, Spell Power (Good) +1
 2	+1	+0	+3	+3 	+1 Level Divine 	Sneak Attack +1d6, Natural Armor +1
 3	+2    +1	+3	+3     --			Draconic Ability, Spell Power (Good) +2
 4	+3    +1	+4	+4	 +1 Level Divine 	Breath Weapon, Natural Armor +2
	 
  Special Abilities:
- Energy Resistance 10 (Ex): This replaces (does not stack with) the racial energy resistance that the metallic kobold chose at character creation. His scales take on a more reflective, metallic sheen.
 
- Natural Armor (Ex): The specified value replaces the metallic kobold's racial Natural Armor bonus.
 
- Spell Power (Good) (Su): When casting good divine spells, the character's Caster Level gains the indicated bonus.
 
- Draconic Ability: The metallic kobold gains one ability based on its scale color as follows:
                  - Gold: Extra +1 Natural Armor bonus (Ex)
                  - Bronze: Water Breathing (Ex)
                  - Brass: Create Water (Sp): 3/day, caster level = character level
                - Silver: Cloudwalking (Su)
                - Copper: +5 save vs. poison (Ex) 
- Breath Weapon (Su): The metallic kobold may use this special attack up to 4/day as a standard action once every minute. The DC is 10 + 1/2 the Kobold's character level + Con bonus, and the breath weapon deals 4d8 damage in the type & shape indicated:
                  - Gold: 15 ft. cone of Fire
                  - Brass: 15 ft. cone of Fire
                  - Bronze: 30 ft. line of Electricity
                  - Copper: 30 ft. line of Acid
                  - Silver: 15 ft. cone of Cold