Step 1: Supplies
Gather these supplies to make your extract:
Vanilla Beans (1 oz per cup alcohol/30 grams per 250 ml alcohol)
Get the best beans you can, but don't get ripped off by outrageous prices. Search the internet and eBay for some really decent vanilla bean prices. Grade 'B' beans (also called "extract grade") will give the most vanilla flavor per kilo of beans.
We could go with the FDA requirement and use about 0.8 oz beans per cup of extract, but this probably wouldn't be strong enough. Industrial vanilla extractors are orders of magnitude more efficient than our hand extraction process. We need to add more beans to get anywhere near extract concentration. I recommend a minimum of 1 oz (~8 beans) per cup, but shoot for more. Remember: professional bakers use 2-fold extracts, it can't be too strong.
The beans shown in this instructable are Amadeus Trading's Uganda Gold (tm) Vanilla beans. These beans were the obvious choice because their large size made for great pictures.
Dark Glass bottle with tight fitting cap.
Green or brown wine bottles work best. Dark glass protects the extract from direct sun exposure. Make sure you have a tight-fitting cork or lid that can be easily removed (you cannot resist smelling it during the extraction!).
Vodka (37.5-40% alcohol, 75-80 proof)
Consider a decent quality vodka, as you could have this extract for 10 years or more. A super high proof (more alcohol) vodka might not extract as much vanilla goodness ( reference ). Commercial vanilla extracts are 35% alcohol, by law. Leave some room in your calculations for the water that the beans will contribute.
Sharp knife and cutting board
To slice the beans in half and remove the seeds.
Steamer or pot of boiling water
Though optional, I always sterilize any implements that will come into contact with the bean or extract. Any yuck will sit in the bottle and contribute off-flavors for years. Why risk it? Steam or boil a clean bottle, cap, and knife for 30 minutes just prior to use.
Clean work area
Its probably not a huge concern, but you don't want strong odors floating around when you prepare extract. Unless you intend for your vanilla to have smoked salmon undertones.
Some, but not a lot. Our vanilla can be used after 4 weeks, even though the extraction will continue for 6 months. When the extraction is finished the vanilla will continue to mature indefinitely. It's like having a fine wine that can be sampled continuously as it ages over decades.