Feet/ footers: Cones, pads, rubber gizmos, fancy gizmos, roller gizmos

Aside from the shelving stuff, what do you add under your equipment feet?  
Nothing?  
Hard cones.. metal. wood.. with under disc, right into shelf?  
Soft footers. pads, half domes.. sorbothane...    ?  
fancy aftermarket footers?   Brass...    ? 
Roller devices?  
Added butcher block rests...  thck thin, IKEA... ?Other?   
I have used all sorts of stuff under my equipment. My favorite go to are size ten butyl rubber bottle stoppers, then under really heavy stuff, old Tip Toes, and under some things sorbothane half domes. But no expensive doodads.   
I have recently tried some home made rollers, no improvement to negative results. 
Mostly I like some vibration dampening.. hard connections seem to go negative on quality of the sound   
So I am just thinking about feet. footers. What are your experiences with them?