Old glass insulators for weights to hold anything down.
Would love to get my hands on some ... I use the old sad irons for weights!
My favorite weights are "3rd Hands". You just sew some about 4" squares or rounds of about 4" - right sides together - sew them twice. Leave a little hole on one side about an inch across.
Turn - poke out the corners.
and FILL THEM WITH PENNIES! Takes a few dollars worth,
and they are heavy enough to hold anything down. Because they have a fabric surface they don't slip and they are heavy enough to keep fabric from slipping.
That is why they call them a "Third Hand" !