You might be able to find some molding panels like the lower part and then just add the upper part your self. Have you ever worked with making molding ? It requires good tools and a lot of skill to make it perfect and not just a DIY mess I have actually used cabinet doors sometimes.

Molding should be sized to the area it's going into. For example baseboard height should be a minimum of 1/2" per foot height of the wall. There are books that explain the rules of 3 and rules of 5 etc...