Is this honest-to-goodness lead or is it some other material? Well done on the job and, of course, the photos!
Weighting plastic chess pieces with lead shot - DONE

Is this honest-to-goodness lead or is it some other material? Well done on the job and, of course, the photos!
The cheap lead shot from Amazon is 99.9% lead. Be careful if using lead. I overfilled the hole with CA glue to fully encase the lead shot inside the piece. Took about 12 hours to fully dry/cure.
I've had this cool travel chess set for a while now. 1.5" sq silicone board. 2.5" King. I love the small, lightweight, indestructible silicone board and hollow plastic pieces. It barely takes up any space and packs well in a backpack or suitcase for trips. One thing I don't like about it is that since the pieces are small and made of hollow plastic, they fall over with the slightest touch and bump. If you accidentally knock the table with your knee, half the pieces are down! Let's fix this.
Emboldened by my recent Chavet project (here), I think it's time this travel chess set got an upgrade. I carefully filled the hollow crevice of each plastic piece with lead shot. Slowly dripped CA glue into the lead shot filled hole. Used painter's tape to prop them upside down for drying. Used the same process of measuring and cutting stiffened felt with a compass cutter. Spray adhesive. Match up the sizes to the bottoms. Press. Done!
The playability of this set is so much nicer now. Like night and day. Using lead shot, I almost doubled the weight of the pieces. In hindsight, because the hollow spaces were so small, maybe I should've used tungsten powder to maximize the weight to size ratio. But I was being cheap. Tungsten is pretty pricey. The tungsten powder would've cost more than this cheap travel chess set. Hah!