This is probably the easiest way to make money on Runescape.
Step 1: The First Step
The first thing you need to do is buy 13 buckets a grand exchange. Then fill the buckets with water.
Step 2: The Clay
After the buckets are filled with water you need to buy or mine clay,not soft clay. You will need 13 also. These can also be bought at the grand exchange.Must by for full price.
Step 3: The Mix
Once you have 13 of each you can mix them to getter and make soft clay.
Step 4: The Money
Finaly sell your finished product at the grand exchange, but it has to be sold for lowest price. The 13 soft clays will sell for double of what you spent. Repeat steps until rich.
Also i cant take credit for this idea, give the credit to purerange9ka.