Plumbers glue can also be used as it is safe after it completely dries. BUT, it does emit toxic fumes during the application process and should be used in a well ventilated area that is in a separate building from your birds. Acrylic and Marbella plastic also emit toxic fumes during the cutting and drilling process so take special care while performing these processes. I only recommend that cotton rope toys be used under direct supervision. As the cotton rope frays, it becomes a dangerous deadly trap.
Birds can become entangled in the frayed pieces.
Injuries that have resulted from being caught in rope toys range from amputation of single digits to an entire foot. The worst cases that I know of are birds who strangled to death while struggling to free themselves. I have seen many toys I would love to buy for my Amazons but won't because of the bell that is put on the toy. Some of these bells are downright dangerous. The material they used to make the bell.