I have cut out simple cardboard profiles using the sketches featured above from some scrap corrugated cardboard.
These profiles were glued together with my Hot Glue gun and thinner cardboard was used for the front and back cladding of the forge.
During the gluing process I added one extra profile (compared to the plan) as I thought it looked a little too small when I placed a 28mm figure to the side.
Lead Adventure Build Something 2015 link
Always have at least one miniature to hand when you are building terrain and use it to test out the dimensions of the model, particularly the building height and the size of doorways.
More updates to follow.