Simple swivelling casters, for relatively lightweight furniture. Although I seem to be able to lean most of my weight on one with no trouble at all, you might want to do a destructive strength test on a printed hub before fitting this on something like a couch/sofa.
Since a couple of castors somehow fell off an item of furniture when moving out of my last flat, I figured I would try out printing replacements, since buying just a couple of new ones seemed about as expensive as printing them (getting ones that actually fit this thing were more so).
The kind of castor that I'm substituting this for is shown, and I've also made a wheel version with 1mm walls and spoke-like infill (cross-section pictured) as part of the model in a similar form to those injection-moulded wheels. This should optimise strength/weight ratio, but feel free to use the blank model with any infill style you prefer.