These FineScale models are molded entirely in tough ABS plastic... We consider them to be "Craftsman" type kits because assembly is required and to differentiate them from the "RTR" and "shake the box" stuff available elsewhere... The kits are not weighted but a precision cut weight kit that fits inside the center sills is available separately for an additional $9.95, in case you wish to operate your model empty... Copyright 2016 - GLACIER PARK MODELS ® All rights reserved.