Materials:
1. some pennies (around 15 each)
2. electrical tape
3. sludge, goo, slime, etc (for info on how to make sludge please visit Terra Genesis look in the readers terrain tip section)
step1: Stack around 15 on top of each other.
step2: wrap electrical tape around them.
step3: put the sludge on top.
There you have it! Some people take an extra pennie, wrap it up completly in tape, and use it as a a lid!