in the lower channels 20 of the pack section while the warmest portion of the fluid to be outputted from the upper channels 20 of the pack section 12 reinforces the coolest portion of the fluid initially inputted into the lower channels 20 of the pack section 11 thereby substantially equalizing or at least tending to equalize the temperature over the entire exterior surface area 14 of the lower pack section 11 the method of making the therapeutic thermal pack unit 10 of the present invention contemplates the steps of forming first and second half sections which are substantial mirror images of one another each having a header portion and a plurality of elongated generally parallel channels therein and then placing a separator sheet atop the channels so that one end of the sheet forms an outer boundary of the header portion while the opposite end of the sheet terminates a predetermined distance from the ends of the channels the other half section is then placed over the first half section with the separator sheet disposed therein so that the sheet assumes a similar position with respect to the second half section the two sections are then secured together such that their channeled interiors are facing one another and the separator sheet is sandwiched therebetween to form a fluid type seal at the header ends.