also be a solid e g calcium titanate magnesium titanate strontium titanate aluminum oxide titanium dioxide glass etc due to the low dielectric constant of glass u03b5 r 4 to 8 there will be less field concentration however since the dielectric constant of glass depends upon its composition it might be possible to design a composition with a high dielectric constant in particular barium titanate is a good choice u03b5 r 1143 in general the higher the dielectric constant and the lower the dielectric loss the better the material is for use as a hdcm preferably any material with a relative dielectric constant of at least 10 can be used when using a solid hdcm 24 it can be possible that the losses therein can be low enough so that pump 30 radiator 32 and pipe 34 can be eliminated otherwise internal channels or passages can be disposed in hdcm 24 for passage of a cooling medium the effect of hdcm 24 is to concentrate the field lines 14 at a annular localized area 26 of workpiece 16 to provide localized heating and softening subsequently workpiece 16 is placed in male and female molds and area 26 is stretched to make a desired object e g a waste receptacle in the second embodiment of fig3 electrodes 12 are shown as being elliptical in cross section to provide a uniform field to wide ends 20 and disposed exterior of the containers 18 however there.