The ornamental design for a base of a shippingcontainer, as shown and described.
FIG. 1 is perspective view of a base of a shipping container according to the present invention illustrating environmental structure in broken lines that does not form part of the claimed design;
FIG. 2 is top perspective view of the base of a shipping container according to the present invention;
FIG. 3 is bottom perspective view of the base;
FIG. 4 is a front elevation view of the base;
FIG. 5 is a rear elevation view of the base;
FIG. 6 is a left side elevation view of the base;
FIG. 7 is a right side elevation view of the base;
FIG. 8 is a top plan view of the base; and,
FIG. 9 is a bottom plan view of the base.
The broken lines in FIG. 1 showing side walls of a shipping container are provided for the purpose of illustrating environmental structure and do not form part of the claimed design. The broken lines in FIGS. 2 and 8 illustrate a top surface portion of the base that forms no part of the patented design.