Vintage sequins - sure - they were designed to be sewn on clothing, and you could do that. What else can you think of? For one thing, they are pretty cool strung between small beads. Small bead caps? Float in resin? Packed by volume. Some settling may occur. Approx 700 in 3 grams, and I do mean approximately - these are a b---- to count.
7mm By the pack of 3 grams.