A block is a wooden tool used for shaping gathers of glass. After a glassblower gathers hot glass from the glory hole, he or she takes the glass over to a bench to begin working it. Blocks. 50 Devardi Glass Clear Boro Tubes Lampworking, Glass Blowing COE 33 ~ 8, 12 & 16mm DevardiGlass (330) €48.24 12 Devardi Glass Clear Boro Tubes Lampworking, Glass Blowing.