phys-rock.

[Sierra Katrian]

Pebbles? I don't see those working. They have to be bigger than an eye socket in order to be legal.
And because rocks are throwing weapons, you cannot weight them with anything.

You cannot use spell packets, as spell packets are used for spells.

My Jericho character uses rocks as her secondary weapon, and they are about 2 (small) fists in size, made of dollarama sponges, plastic wrap, and duct tape.