A Druid is the same in all ways as a Cleric of equal level (hit dice, attack progression, saving throws, spells per day chart, etc) except for the following:
- A Druid uses the Druid spell lists, not the Cleric lists, see the Companion and Master rule sets for these lists.
- A Druid may never wear armor made from metal. Hide, leather, bone, etc are acceptable, and buckles and other incidental hardware don't count, but chain and plate mail, and similar non-standard armors are forbidden.
- Likewise, although a druid is not bound by the Cleric's limitation on weapon use (Druids can use piercing and slashing weapons), they may not use metallic weapons, this includes weapons like arrows and maces that may be mainly composed of wood but have a metallic head. Wood, stone, bone, horn, etc are all acceptable.
Pretty simple. I see no need to create a whole new class with different saves, experience progression and other features. Just tweak the armor and weapon allowance and switch to the Druid spell list.