Step One: Find some rock. It could be from an aquarium store, it could be from a garden center, or it could from where they blasted nearby my house to put in a gas pipeline.
Step Two: Barbecue the rock. They autoclave laboratory equipment at 121 degrees Celsius under pressure for fifteen minutes to sterilize it. I don't have an autoclave so half an hour at 250 degrees Celsius ought to do.

Step Three: Bleach the rock, scrub the rock, then soak the rock for a couple of days. Even though the blasting happened over 10 years ago, and the rock has been weathered all this time, there might still be dangerous chemicals clinging to it.

Step Four: Find a hammer...

Step Five:
Use said hammer. Smash the rocks into smallish pieces. Don't worry about sharp edges, they will be smoothed down in a later step. Wear safety goggles so no rock shards fly into your eyes.

To be continued...
Step Two: Barbecue the rock. They autoclave laboratory equipment at 121 degrees Celsius under pressure for fifteen minutes to sterilize it. I don't have an autoclave so half an hour at 250 degrees Celsius ought to do.

Step Three: Bleach the rock, scrub the rock, then soak the rock for a couple of days. Even though the blasting happened over 10 years ago, and the rock has been weathered all this time, there might still be dangerous chemicals clinging to it.

Step Four: Find a hammer...

Step Five:
Use said hammer. Smash the rocks into smallish pieces. Don't worry about sharp edges, they will be smoothed down in a later step. Wear safety goggles so no rock shards fly into your eyes.


To be continued...