Little bricks, lots and lots of little bricks.
I figure in 20 years I'll have enough to build a tufa house.:)

Actually I'm covering my shed wall with them.
It's my "Shed of many Colors"

Frogs...

Small rock shapes with cute sayings like HOPE PEACE LOVE stuff like that. Also Dog names or breeds (my girlfriend grooms dogs and cats).
Paws

Just some flat 6" circles to test surface treatments on.

Sue

I throw it in smaller plastic containers with some leaves in the bottom, pop a hanger on the back, and it makes a nice leaf impression plaque to hang somewhere like a fence.

Jilly

tuffa balls, pleaf plaques, small sedum planters

I shape leftovers into small discs or into little balls - the size of a cherry or plum. These get stored in an old bucket. Then, if I'm filling a mold with new 'tufa & find that I haven't mixed quite enough, I dip a few of these in water & then submerge them in the mix that's sitting in the mold to raise the mix to the needed level.

Bump