I finally got my lazy ass around to ordering the agar-agar I needed to get this project rolling. For the last couple months I've had everything I needed except the agar-agar, which I just got in the mail today. So without further ado, I'll detail the process I used tonight for the first part of this project.
Step 1: Gather Supplies
Dry malt extract x 1 oz
Petri dishes x 1-10
Agar-agar x 1 tbsp
Container for sanitizer water
Step 2: Prepare Sanitizer
Should be pretty straightforward. Follow mixing directions on the bottle of sanitizer.
Step 3: Measure out DME and Agar-agar
I used 1 oz of DME in 2 cups of water for an approximate wort gravity of 1.020. As stated earlier, I used 1 tbsp of agar-agar.
Step 4: Heat Water and Add Ingredients
After bringing the water to a boil add the DME and mix thoroughly. Be very careful to avoid boil overs at this point. I had a hard time getting the boil to settle down after adding the DME. Once the DME is fully mixed in, add the agar-agar. The agar-agar will clump up a lot, but enough should be immediately dissolved to set properly once the temperature comes down. I would still try to get as much dissolved as possible, though. Continue boiling for about 5 minutes after adding the agar-agar.
Step 5: Transfer to Petri Dishes
Remove the mixture from the heat and use the sanitized turkey baster to transfer the mixture to the sanitized petri dishes. I used plastic petri dishes so I was able to transfer straight away without the need for cooling the mixture. If you're using glass petri dishes, make sure the mixture is sufficiently cooled. You don't want it too cool, though, since agar-agar will set at room temperature. At this point I placed my petri dishes on a cookie sheet and into the refrigerator so they would set faster. Even in the fridge I was surprised they had set within 15 minutes.
Step 6: Try to Catch Some Yeast
I placed my petri dishes next to an open window to minimize the chance of a bug getting in there and messing things up, but you could set them outside if you wanted to. Just be sure to make some sort of protective barrier that will allow air (and therefore yeast) in but keep bugs out. I left the dishes by the window for 2.5 hours.
Step 7: Incubate
The last step is to place the sanitized lids on top of the dishes and place them in area that will have temperatures suitable for incubating anything that landed on your dishes. I have a tool box in my garage where it gets to around 80-90 F during the day so I set my dishes on top to wait for a week or so.
Hopefully this works since my last attempt at local yeast wrangling went horribly awry. We'll find out soon and I will report back when I start seeing some growth. Until then, happy brewing and happy drinking!