Thinner plastic allows the soil to heat up better but also tears more easily. Use plastic with a thickness of 1 to 4 mils for best results. Fill in the ditch around the perimeter with soil to hold the plastic in place. You may also wish to add rocks to the edges to help hold down the plastic.
The didgeridoo is a wind instrument traditionally made from the trunk of termite hollowed eucalyptus trees from Australia (like the one pictured at left, which is being played by our mate Lewis Burns).
If you are looking to buy or give a didgeridoo as a gift, try to avoid a teak or bamboo copy which robs the Indigenous Aborigines of their cultural heritage; the consumer can make a difference and help the traditional Aboriginal crafts people by choosing to by an authentic traditional instrument from a reputable source.