As to muck for bonsai I've tag mine with the name of "Bonsai Sausage".  The reason
I did this is the way I handle it. My muck recipe is no different then the majority (50% earth clay, 35% chopped sphagnum moss and 15 % fine sand).

Any time you prepare muck it's always a big mess. So what I do is make up a big
supply at one time. After I have mixed it to the right consistency (Like pie dough)
by adding water (contains Peter's 20-20-20) slowly, I then roll it into rolls about
2" thick and about 16" long then I place each roll on plastic saran wrap/cling wrap
about 22" long and then I roll it up tightly and I tie the ends together and ending up
with rings that look like either bologna sausage or polish sausage rings; hence the
name "Bonsai Sausage".

I take these rings and place them in a container and store them in the freezer. So a day or two before I'm going to do forest planting on a slab or a rock planting I take how many rings I figure I'm going to need from the freezer and let then thaw out and then they are ready to go.

I find that my mixture is just right for making the dike on slabs for containing the soil. I also take sections of the roll and make them into a sausage patty shape to place on the slab for holding the trees into place. Then I'll add my bonsai soil around the trees and inside of the dike. I add green moss on the muck. My muck mixture works great for placing roots over rock planting. Any left over muck I just roll back up and put it back into the freezer for a later date. Works great for me!. So down the road if you ever hear the name "Bonsai Sausage" you'll know how the name came about.