The heat transport between liquid3He and five different small metal particle ‘‘sintered’’ sponges are directly compared in the temperature range from 7 to 70 mK through measurements on five cells which are identical in every way except for the nature of the sponge. Fine (0.1–1 &mgr;m) powders of copper, silver, and palladium are formed into sponges that are bonded to the walls of a copper container using various packing and heat‐treatment techniques. Each container, fitted with a resistance thermometer and heater and filled with liquid3He at a pressure varying from 3 to 15 bars, is then used as a heat exchanger between a dilution refrigerator and the3He. The palladium sponge, per unit surface area, has the lowest thermal resistance (R) to liquid3He, but is the most difficult heat exchanger to make. The silver sponge, per unit volume, has the lowestRand is by far the simplest heat exchanger to build, requiring only cold packing with no heat treatment, yet performs as well or better than those discussed previously in the literature.