FIG. 1 is a rear perspective view of the dumbbell support cradle showing my new design; FIG. 2 is a side elevation view thereof; FIG. 3 is a rear elevation view thereof; FIG. 4 is a front elevation view thereof FIG. 5 is a top plan view thereof; and, FIG. 6 is a bottom plan view thereof. The broken lines depict environmental structure and do not form a part of the claim.