Old school blender and mason jars?
 

https://www.phillipsfiberart.com/colorin-quilts-faq.htm

Day 2 says put mason jars on base of old school blender. I have no idea what that means and I am very old school. LOL Anyone know?

It's the Laundry Sauce recipe.

I think the base of the blender with the blades can screw onto a mason jar.

Perfect opportunity to go to the thrift store, should be blenders and jars to try them out. But yes, the thread and size could be the same... or not, so check out first.

The mason jar must screw onto this, I think that is what the recipe is calling for:

https://www.oster.com/parts-and-acce...7-000-000.html

Having the jar upside down is what seems so confusing to me.

The Ninja blenders have attachments that do this:
https://www.ninjakitchen.com/support...tri-ninja-pro/

Seems backwards but you put the ingredients in the jar and then put the base of the blender on like a lid.

I had a set of little pint containers that also had lids, you could mix up the stuff like pancake mix in the blender and then put it on the shelf.

I have a blender that is 34 years old. Got it when I had my first child to make baby food. The part that holds the blades to the blender container is the same size as a standard neck mason jar. The blender came with mini jars, that are not open at the top and standard mason lids fit on them.

So without going to the recipe, I woudl guess that this is what it refers to. You can attach a standard, not wide mouth, mason jar the the part that holds the blades to a blender contain on some older blender models.

I think that's it. I had a 30+ year old blender that you could do that with. It was handy if you wanted to blend a small amount of something.