Where to find steel dome cones for speakers


Hi I have a pair of speakers that I would like install steel dome cones on the bottom so I can slide speakers around.  I'm not interested in flat sliders. I've searched partsexpress, audioadvisor, acousticsounds, eBay, Amazon etc without luck.  Any help would be appreciated.
dracule1
Acorn Cap Nuts ?

https://www.zoro.com/value-brand-cap-nut-m20-250mm-gr-a2-ss-plain-6ce11/i/G2144186/
https://www.ebay.com/i/321944896919?chn=ps&dispItem=1
thank you imhififan.
Looks like those are not the ones I recall want.  I've seen ones specifically for audio equipment that were half spheres and about 1.5 to 2 inches in diameter.
Herbies Audio Lab might have what you need. 

N
Looks like those are not the ones I recall want. I’ve seen ones specifically for audio equipment that were half spheres and about 1.5 to 2 inches in diameter.
http://magico.net/product/qpod.php
or
http://shop.mapleshadestore.com/Radiused-Footers/products/152/

http://www.ebay.com/itm/3Pcs-Solid-Steel-HiFi-Equipment-Speaker-AMP-CD-Isolation-Spike-Feet-Stand-Ba...