I am glad this tutorial got all of your creative juices flowing! Be sure to look up the other way to antique the cabinets. IT DOESN'T CALL FOR WAX. I believe it's under Making a kitchen dresser from mat board.
For 1/2 scale, I would use the mat board for the cabinets. For the doors try to find something thinner, poster board? You don't have to make the whole thing, try making a door first, use a couple of layers of card stock for the second layer on the doors. I wouldn't worry about sanding the shape on the poster board or card stock, I don't think it could be done with satisfaction. Finish the door to see if it will take the paint and other finishes. Be sure to seal the edges of the poster board. If this works than I would go ahead and make your 1/2 scale kitchen cabinets.