When curing the mix, the wood will float so I set the pan between two bricks so sides wont bulge and set a 3rd brick across the pan pushing the wood down so it will be flush with the top of pan. Don't leave it to dry fully! When its still slightly grey it will save you a headachee if run a putty knife along the walls of the block and pan as well. i do this three times as its curing. now i have what looks like a block to fill the lower half of a pan the same as before but with no gaps between any of pans walls, this is for the lid. pour some graphite powder evenly coat the wood before u pour same refractory with more plaster and less sand plot your holes and do some pilots while its still muddy then again right before almost dry. add a thin layer of plaster around edges and plop the1st form upside down on the the second. its tedious but worth it... before joining u can slice out the entry hole and for more consistant flame i cut a square of stainless and float it centered in the first form to break the straight flow from purge out to uneven
will post pictures of one i have almost done with what stuff