3/8” x 18” acrylic rods. I’ll drill holes in rock and skewer them with rods, glueing the seams. Then glue accelerator spray. Dry. Very runny glue on dried glue seams so sprinkle sand on runny glue to hide glue. Blow off excess sand with canned air. Bottom pic little tiny bag of aquarium sand just for 10 tank. Perfect amount, won’t waste a bag of sand.