1 A do-it-yourself approach for basic basement steps starts around $250-$350 for materials, and takes about 3-4 hours. 2  That's with standard lumber, such as pine; costs can go much higher with more expensive wood, such as oak.
Pour enough melted agar into each sterile plastic petri dish to cover the bottom - about 1/8 to 1/4 deep. Replace the lid immediately. Place agar plates on a counter top to cool and set. Agar medium will set like stiff gelatin at room temperature. The agar medium is now ready for storage or use.
Remember, the lid of your cooler should not be shut air tight but loosely in order to allow the dry ice to sublimate, or turn from a solid to a gas, and always take care to handle the dry ice safely by wearing gloves or using a towel. You can find more safe dry ice handling advice in our Dry Ice Safety blog post.