Can I repair a luggage caster housing with Sugru?
It's unlikely that suguru will be durable enough for your requirements. It's a flexible material, but not a high-wear sort of product.

On the other hand, if the hand-moldable aspect of suguru fits your needs, you may find that hand-moldable plastic will work better. It's poly-type plastic, relatively slippery but quite strong when cool.

I've used the stuff for various projects in the past. The instructions suggest to put a baggie of pellets in hot water and when they change from opaque to clear, form in place to create the desired object. I'm impatient and discovered that one can build a tiny tin foil tray and use a hot air gun. This method saves time and creates incredibly hot plastic which burns skin. It's the timing that matters, as one can begin to use the plastic once it is completely clear and not burn one's skin as easily.



The above link points to Michaels' stores, while a similar product can be found on Amazon as well as many other locations on the 'net.