This is more about model design than aerodynamics so it's been moved to Scratch Building.

For the tail in order to get a nice looking symetrical airfoil I'd suggest you use something like a hinging tool to scribe an inset line along the trailing edge and then push in spines of 1/8 wide 1/16 plywood or carbon strip so you can sand down to a very sharp trailing edge to allow you to better get the shape you're after. Otherwise for practical handling considerations you have to leave it quite a bit thicker.