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.
Start pouring the dishes in a rythmic manner starting from the bottom plate and working your way up. Add just enough agar so that the bottom of the dish is completely covered. Try to leave the lid of the petri dish open for as little time as possible. Also, ensure no part of your hands touches the inside of the dish.