Preferably, use a perforating wheel to cut,
but in lack of such, you can cut along lines with a scalpel,
taking care to not cut all the way to the edge.
Designed in 1981 by Mart van Schijndel, a Dutch design icon. Consisting of three sheets of glass held together with three perfect silicone joins, it doesn't get more minimal than this. Made by hand - this is not art pottery, but a glass extravaganza. The Delta vase is included in the permanent collection of the MoMA in New York and the Stedelijk Museum in Amsterdam. One of my all-time favorite objects, it is so pure, I appreciate the clarity, no pun intended.