It's actually very easy. If you'd like to grow your own baby African violet just snap off a green leaf of a healthy plant and put it in a shot glass filled half way with water.
Place it in a windowsill with indirect sunlight and wait until roots will appear, in about 2 weeks. Don't forget to add some water to a shot glass when needed. Watch your plant because you don't want to overgrow the root system.
So here is what you need to plant 1 leaf:
2 plastic cups
African violets soil mixture (you will find it at almost any garden center)
dull knife or similar tool for planting
sharp pointy knife or a tool for making holes in a cup
1 leaf with developed roots
Liquid fertilizer for African violets (for future care, do not use when planting)
Make about 5 small drainage holes in a bottom of one glass, write the date of planting on a side with a permanent marker.
Fill this glass with planting soil and water thoroughly with lukewarm water. The soil should be completely moist. Now, with your dull knife make about an inch hole in a middle of the soil and carefully place your rooted leaf. Hold it with one hand and move some soil to the middle to support the leaf. Stick this glass to another one and place it in a windowsill with bright indirect light and no drafts.
Water your new plant about once a week or more often, depends on how dry the air is in your area. Always use a lukewarm water to water it and some African violets fertilizer with each watering. Give it some time and you will see the small leaves will appear around the base of leaf.
It will get bigger and bigger every day and one day you will see some little flowers appear!
When it happen you will know that your baby plant is happy and singing!