Thanks for the novel approach but chain end holding tools have been around for a long time and a home made version is easy to make using a piece of steel wire and a pair of pliers. Coat hanger wire is ideal for this and free nearly everywhere. Cut a piece of the wire about 6-7 inches (1- 185 cm for our metric using members) long and bend it into a shallow U-shape. Then bend about 1/2" (12 mm) of each end inward are about 120° to form shallow hooks. Hook the ends into each end of the chain spanning the open link and leaving enough slack to install the master link or joining pin.