In this video, I show how to build the 3 Easiest TNT Cannon Designs in Minecraft 1.21.4!
The first TNT cannon design is short-range. Next is a mid-range design TNT Cannon, and lastly I show a long-range TNT cannon.
All of them are very easy to build and all the materials are shown in the video.
These TNT Cannon Designs work on Java edition in version 1.21.4 and below. I did not test it on the Bedrock edition.