In order to form a mobile wheel base, a stem caster adapter or a wheel assembly are attached to the bottom of a platform support or a container such as a cardboard carton are provided. The adapter has a body with a cylindrical recess open at the bottom surface adapted to receive and engage the stem of the caster. In the wheel assembly, a wheel or roller is rotatably attached to the bottom of the body. Both the adapter and wheel assembly have a cylindrical member extending from the top surface of the body with oppositely extending protrusions forming a bayonet-type mount. The mount is received within an opening in the bottom of the platform support or container and then rotated to attach the adapter or wheel assembly to the platform support or container.