Movable Blocks. US Block Windows' operable acrylic-block windows provide the appearance and privacy features of conventional glass blocks - but they open and close. Single-hung, slider, awning, and casement styles in three frame colors and seven block patterns are available. The company also offers custom shapes, including arch-tops, eyebrows, and hexagons. Prices range from $300 to more than $2,000. US Block Windows, 888/256-2599, usblockwindows.com.