So I recently made a large batch of MMF. I let it sit for a day or so (didn't refrigerate it) and then started to color portions of it. While working with it, I noticed that it seems less pliable than I'm use to. More elastic....almost too elastic. I think it will be fine for covering a cake, but I'm having a heck of a time using it for modeling anything.

I made a larger batch than usual...maybe I didn't add enough water? Maybe I need to knead it longer? Any suggestions?

If it is too "elastic" I am betting you didn't add enough powdered sugar. After my MMF sets overnight (NOTrefrigerated) it is hard - I have to microwave it a few seconds to get it to where I can work it.

MMF by itself is not a good medium to mold things with, you need to mix it 50/50 with gumpaste or add some tylose to it for that kind of work.

It sounds like you may need to add more ps to get it stiffer. However; like the OP stated you may need to mix with gumpaste it to make it more "moldable".