ALG Defence makes aluminum ones they say weigh .5 oz which is close to .5 oz lighter than the steel ones.
Problem is the price and availability.
Pretty much out of stock everywhere and roughly $70 a pair to save 1oz.....
The ALG Forged QD Sling Swivel (FSS) is a lightweight yet heavy-duty sling swivel option. The standard QD configuration makes it compatible with any device that accepts QD accessories. The FSS is 1 inch in size and weighs roughly 0.5 ounces and is about half the weight of similar steel QD sling...
algdefense.com