the styrofoam columns it was necessary to insert a 1-1/4" thinwall conduit core in each. While it might have been possible to rout out a su itable recess using the hot wire or by other means, it would have been fairly difficult to achieve the really tight fit deemed necessary structurally. A close fit would have been even more difficult for the Roman arch shaped cores of the Gothic arches (also shown in Fig. 8). Precise fittings of these unrelated forms would have been most difficult. To avoid this difficulty it was decided to allow the core to form its own recess. A piece of heavy asbestos covered wire was passed th rough the tubing and connected to the hot wire supply in place of the knife. Thus the asbestos wire became a heating element capable of heating the tubing evenly along its entire length. By carefully controlling temperature and pressure it was hoped that the tubing core could be made to melt out its own recess. Since styrofoam is a thermoplastic it was further hoped that a certain amount of bonding might take place. A small scale prototype of this scheme seemed promising. Regrettably this process did not function properly with the full size units primarily because the multi-tap power supply described here was not available. A higher supply voltage was apparently necessary to overcome the increased resistance of the longer and thinner (12 AW.G.) asbestos covered wire available. Recent experimentation using the 18 V tap on the power supply has shown this scheme to be feasible (Fig. 9j. The adhesion of the styrofoam to the core in the experimental sample shown is excellent. The technique is critical nonetheless. Figure 9. An experimental method for imbedding thinwall conduit into styrofoam. When heating is properly con· trolled, adhesion is excellent. Figure 10. An experimental hand operated "Lathe" for producing turned shapes. Again, the scrap has been removed for clarity. The ridges are typical of cuts made through built up layers and are easily removed with sandpaper. 12 ~ THEATRE DESIGN AND TECHfl,jOLOGY DECEMBER. 1973