Fire bricks are available in Daro.. you see them on the sidewalks on both sides of the national road. All come from the same supplier and cost the same. 8 to 10p each depending on delivery area. Any good hollow block worker can lay them up for you, but best you pull up a lawn chair and supervise while it's going up. Buy the premium cement (few peso's more per bag), seems to have less contaminants in it and makes for a smoother mix. If you want a "pizza/bread" style oven there are many designs and plans online. Be very careful of the opening measurement as it's critical for the draft and quality of the oven's performance. A well built oven should not smoke at all and draw very evenly throughout... PM me if you need any more help, happy to offer my 2 bits worth. Gerry