Homemade laundry detergent (and it's HE / high efficiency compatible)

So we've been using homemade laundry detergent for a few months now.  It's incredibly easy!  And, despite the fact that it's a powder, it is compatible with high efficiency / front-loading washers.  Here's how to make it.

Ingredients:
1 bar of soap
1 cup of washing soda
1 cup of borax

Grate the soap finely.  Easy!  This will yield about a cup of soap powder.

Then add a cup each of the borax and washing soda:

And that's it!  Mix it together well -- use a whisk if you want, or even a blender -- then toss it in a container (in our case, a big plastic jar that was previously full of cashews), and start using it.  One tablespoon does a load.  I'd initially made a scoop out of the folded end of a toilet roll (as pictured below), but have subsequently found a plastic tablespoon scoop from something else we had laying around the house...some other detergent, or coffee, or some such thing.

I've talked to people who are skeptical of using powder in a HE / high efficiency / front-loading washer.  And it's correct that you probably shouldn't put the powder in the drawer at the top.  However, I did my research (as you should, too), and for our machine, anyway, it is perfectly fine to use powder.  But, the key is that you have to sprinkle it inside before loading clothes.  Do so, then turn the agitator back and forth a few times.  After 2-3 little turns, most of the detergent will have fallen through the little holes in the agitator.  Load your clothes and wash as normal.

We tested this stuff out a bit tentatively.  And now, we make big batches of it.  It's quick to make, it lasts forever, and it probably only costs cents per load.  I'll leave someone else to do the math, but it's certainly far less than any detergent I've ever used in my life.

We won't be going back to store-bought stuff ever (probably).