The vacuum tube in a CRT can implode if it is broken or punctured. The surrounding air will rush violently into the unsealed vacuum in the CRT, spraying broken glass in every direction. Color CRTs may contain mercury or other potentially toxic materials.
Instructions. Build a hearth for a fireplace that is 16 inches deep, according to This Old House writer Harry Sawyers. This is the standard requirement for municipalities and homeowner associations. The hearth should also extend a minimum of eight inches on either side of the fireplace.
Fire pits usually measure from 20 inches at the small end to 45 inches at the larger end. Small pits generally cost from $50.00 to $250.00 while large pits can cost from $300.00 to $3,000.00 or more. Some people opt for a chiminea. This is a stand-alone fireplace with a conical shape topped by a chimney.