Beginner portal guardian farm

A cheap no drain guardian farm built almost entirely out of dirt and soul sand. You cover the monument spawning area with a dirt platform, run soul sand bubble columns up to nether portals, and the guardians get pushed through into a kill chamber on the nether side while you AFK. The drops fall through hoppers into 20 chests. There is no draining and no perimeter, and the only expensive parts are the obsidian for the portals and the potions you need to survive the monument while building. Single player needs nothing extra, a server needs a chunk loader for the nether side.

The portals have to be at least 128 blocks apart measured in the overworld, not in the nether. taylor9683 uses 133 to be safe.
Kill all three elder guardians first or the mining fatigue makes the build miserable.
On a server the nether side needs a chunk loader, and the creator's own chunk loader video says not to put one next to a portal farm. Nobody in the comments has posted a combination that works.
doorsackk points out the guardians' thorns chip away at you while you stand there, so you cannot AFK in range without mending gear and food.
JohnMouloudKarish removes the campfires and the netherrack in front of the lower glass row and adds half slabs so the guardians cannot see or shoot you.
ashhhyyyy could not get it to work on Bedrock, the guardians never swim into range of the soul sand.