i have made floor fires to weld heavy sections ,all you need is ,a blower, with a blast gate, a short stainless steel tube to make the tweer, steel flexi pipe to join to blower and molding sand to make the pit ,dig a hole and trench for tweer and flexypipe damp the foundry sand ,and ram it down hard ,set the tweer and ram the sand around it ,set the blower up ,throw in some embers and coal, start the fan ,and get your iron hot, 1 hr max,