wine glass Lampshade one Measure the height of a wine glass from rim to top of stem and add one centimetre (11cm). two Measure the diameter of the glass and subtract one centimetre (6.5cm). Add calculations from step one and two together (17.5cm). three Join the shorter edges of two vellum sheets with doublesided tape. From the top of the page, draw a 17.5cm vertical line down the seam, marking the 6.5cm point.