Elastomeric joining element retaining devices are disclosed. In an aspect, a retaining device is disclosed which is constructed from an elastomeric material such as polyurethane and designed to receive and align an assembly or “stack-up” of nuts, bolts, washers, and/or other joining elements. The retaining device retains and aligns the assembly, enabling a user to install the assembly accurately without dropping or misaligning portions of the assembly. Such retaining devices ease the process of installing or removing joining elements in hard to reach locations.