I checked around briefly, but I didn’t see anything echoing this exact sentiment: Can we get options in the workshop editor to assign what “type” of object we’re importing so we can get some of the interactions that default items have?
For example, making a food object and being able to mark its property as “edible”, or making a chair and marking the property as “Sittable”/assigning seat slots to bigger seats like couches. Or maybe a plushie setting so we can squeak them like the other ones? 
Though, I wouldn’t mind workarounds, either. Like “seat” items that, like lights, are only visible in the edit mode for the Condos, so we could hide them in anything we want and give our friends the option to sit on top of anything.
