A plastic explosive is defined as "an explosive material in flexible or elastic sheet form formulated with one or more high explosives which in their pure form has a vapor pressure less than 10<4> Pa at a temperature of 25 °C, is formulated with a binder material, and is as a mixture malleable or flexible at normal room temperature." [18 U.S.C. 841(q); 27 CFR 555.180(d)(4)]