EN: I design the concept in my mind and then draw it.
ES: Diseño el concepto en mi mente y luego lo dibujo.
PT: Desenho o conceito na minha mente e depois desenho. 
What are the alternatives?
In French a drawing is un dessin and a design is un design. The word design was anglicized to cut down on the confusion I suppose
I see.
So there is no word for design, an alternative then could be “concitualizo a idea na minha mente…”
Talking about french: “un ver vert va vers le verre en verre vert”.
@edil.cajigas, if you’re using the word “design” in the sense of developing/conceptualizing, you can use the translation for those respective words 
There’s also the verb esboçar, for example (to sketch).
Óptimo! É igual a palavra “esbozo” em espanhol.
“Desenho o conceito na minha mente e depois esboço.”
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