If you can't download files (e.g., on a school Chromebook), you can use the , which still works in many 1.8-based versions. Dig a hole 2 blocks deep. Place a Composter at the bottom. Jump inside and place a Piston above your head facing down.
For private servers or single-player worlds, however, experimenting with Eaglercraft Exclusive X-ray hacks is a fascinating way to learn about WebGL, JavaScript reverse-engineering, and game security. xray hacks for eaglercraft exclusive
Click or Add Pack (depending on your specific Eaglercraft client). Upload the .zip file of the X-Ray pack. If you can't download files (e