The trick to glass is not transparency alone but the highlight that makes the edge feel thick. This build uses fills, strokes, and Gaussian Blur inside Appearance so the highlight rides the letterform and updates when you retype.
How it is built
A pale fill becomes the glass body with reduced opacity, a thin white stroke becomes the bevel highlight with a soft blur, and a darker offset fill becomes the shadow that grounds the letter. All three are stacked on one live-text object.
Tip: place the text over a subtle gradient background. Glass needs something behind it to read as “through”.
Watch the full tutorial: Glass text effect tutorial on YouTube.