Get a piece of pine the size you want. Use a fresh utility knife for the horizontal joints, sharp flat blade screwdriver for the vertical joints. Have at it. Knock a little off the corners here and there to age it. You don't want it perfect. Develop a crown on the top you like
When done, paint it with something like Floquil Boxcar Red. Wipe some latex white paint on into the joints, then quickly off. Some black on top.
You'll be surprised how much fun it is!