So just some really basic ideas while I have them on my mind...
Races: Half-elf, Human, Gnome
Alignment: Neutral
A pseudo-hybrid class that hinges on craftable items and guerrilla tactics to win fights.
Generic Abilities: All weapons, Parry/Dodge/Shield Block
Unique Abilities: Discover, Deconstruct, Craft, Brew, Forge Weapon, Forge Armor, Fortify
Discover
Allows the engineer to find materials to work with. Materials come in three types:
Herbs (Can be used to brew special potions)
Minerals (Can be used to forge and fortify items)
Magical (Can be used to alter the effects of Brewed, Forged, and Fortified items)
Deconstruct
Allows the engineer to take something apart and turn it into one or more base components
Craft
Allows the engineer to create basic items out of the materials they discover. Bags, lights, boats, etc.
Brew
Similar to the pre-existing ability, brew would allow engineers to create various potions. They would have a little more control over what they were creating and can brew multiple items together to create hybrid potions.
Forge Weapon/Armor
Allows the engineer to create an armor or weapon. Requires a base item and minerals to forge new item
Fortify
Allows the engineer to fortify a forged item with more minerals, herbals solvents, or magical compounds to create even better armors.
Like I said, a very rough sketch of what I have in mind. I can take time to develop it further, but if you have thoughts, ideas, or contempt and loathing to add, feel free.